How do I use GitHub?

Welcome to the INP GitHub intro. By the end of this page you will have made a real contribution to a real repository: a photo of yourself, merged into this repo by you. No one has to approve it. A bot checks your change and merges it for you, usually within a minute.

Then your face shows up in the collage at the bottom of this page.

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Before you start

• Create a GitHub account: github.com/join
• Install git for your operating system: installation guide
• Create a personal access token: how to. When git asks you for a password, paste the token instead. Your GitHub account password will not work.

The commands you will use today

Command	What it does
git clone <url>	Download a copy of a repository onto your computer
git status	Show which files you have changed
git add -A	Stage all your changes, so git knows what to save
git commit -m "message"	Save the staged changes, with a note about why
git push	Send your saved changes up to GitHub
git pull	Bring down changes other people made

That is genuinely most of what daily git looks like. For everything else, keep this cheat sheet open.

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Add yourself to the collage

1. Fork this repository

A fork is your own copy of someone else's repository. You can do whatever you like in your fork without affecting the original.

Click Fork at the top right of this page, then Create fork.

2. Clone your fork

Cloning downloads your fork onto your laptop. On your fork's page (the URL should have your username in it), click the green Code button and copy the HTTPS URL.

Then in a terminal:

git clone https://github.com/YOUR-USERNAME/INP_Git_Intro.git
cd INP_Git_Intro

Check you cloned the right one before going further. This is the single most common thing to get wrong, and it is much easier to catch now than after you have made your commit:

git remote -v

Both lines must contain your GitHub username. If they say josueortc, you cloned this repository rather than your fork — see Permission denied when pushing at the bottom. It is a one-line fix and you will not lose any work.

3. Add your photo

Put one photo of yourself into the photos/ folder. The filename matters, because the bot uses it to label your photo in the collage:

photos/Firstname_Lastname.jpg

For example, photos/Ada_Lovelace.jpg. Rules:

• One photo, directly inside photos/ — not in a subfolder
• Named Firstname_Lastname with a single underscore between the two names
• Ending in .jpg, .jpeg, or .png
• Smaller than 5 MB
• Change nothing else in the repository

4. Check what you changed

git status

You should see your photo listed as an untracked file. If you see other files listed too, the bot will not merge your change, so undo those first.

5. Save and upload it

git add -A
git commit -m "Add photo of Firstname Lastname"
git push

6. Open a pull request

A pull request asks a repository to take your changes. Go to your fork on GitHub and click Contribute, then Open pull request.

Check the boxes at the top of the page before you submit. The left one (base repository) must say josueortc/INP_Git_Intro. If it says anything else, click it and pick josueortc/INP_Git_Intro from the list. This repository has relatives on GitHub, and the page sometimes guesses the wrong one.

Click Create pull request.

7. Watch it merge itself

Within about a minute a bot will check your pull request. If you followed the rules above, it merges your photo and says so in a comment. You are done — you have contributed to a shared repository.

If something was off, the bot comments explaining exactly what, and leaves your pull request open. Fix it on your laptop, then git add -A, git commit, and git push again. The bot rechecks every time you push. Nothing is broken and nothing is lost.

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If the bot did not merge your pull request

It only merges pull requests that do nothing except add new photos. The usual reasons it declines:

Bot says	What happened	Fix
Not a new file	You edited or replaced an existing photo	Use a filename nobody has used yet
Wrong folder	Your photo is not directly inside photos/	Move it to photos/Firstname_Lastname.jpg
Bad filename	Missing the underscore, has spaces, or the wrong extension	Rename to Firstname_Lastname.jpg
Too large	The photo is over 5 MB	Export a smaller version
Other files changed	You also changed the README, workflows, or anything else	Undo those changes and push again

None of these are a problem, and asking for help is not cheating. That is what the workshop is for.

Permission denied when pushing

If git push fails with something like:

remote: Permission to josueortc/INP_Git_Intro.git denied to your-username.
fatal: unable to access '...': The requested URL returned error: 403

you cloned this repository instead of your own fork. Nobody but the instructor can push here, which is the whole reason you fork first: the fork is yours to push to, and the pull request is how you offer it back.

Your commit is safe. Point the repository at your fork and push again:

# 1. Make sure you have a fork. Click Fork at the top of this page if not.

# 2. Check what you are currently pointed at.
git remote -v

# 3. Repoint it at your fork, using your own username.
git remote set-url origin https://github.com/YOUR-USERNAME/INP_Git_Intro.git

# 4. Confirm it changed, then push.
git remote -v
git push -u origin HEAD

Then continue from step 6 and open your pull request.

A different error: authentication

If instead you see Support for password authentication was removed or you are asked for a username and password over and over, the repository is fine but your credentials are not. Your GitHub account password will not work; you need a personal access token pasted in place of the password. The GitHub CLI handles this for you if you would rather not manage tokens:

gh auth login

The collage

This rebuilds itself every time a photo is merged. Refresh the page a minute after your pull request goes in and look for yourself.

Last year's cohort:

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For instructors

Setup and maintenance notes live in INSTRUCTOR.md.