adding images, updated lesson 01

Author: leahhrlee

git_cheatsheet.md

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+# git cheatsheet
+
+Check whether you have git: `git version`
+
+If not, download git from https://git-scm.com/downloads
+
+
+## Creating local repo
+
+| Instruction | Command |
+|-----------|-----------|
+| create a directory | `mkdir test` |
+| go into directory | `cd test` |
+| initialize git | `git init` |
+| create readme.md | `touch readme.md` |
+| edit readme.md | `nano readme.md` - then make some edits |
+| stage changes | `git add *` |
+| check which files are staged, unstaged, and untracked | `git status` |
+| show unstaged changes between your index and working directory | `git diff` |
+| commit changes | `git commit -m  "create readme"` |
+
+## Working with branches and reverting changes
+
+First, make some changes and create several commits. Then:
+
+| Instruction | Command |
+|---------|-------------|
+| check all local branches | `git branch` |
+| if your main branch is named “master”, do this | `git branch -m main` |
+| see commit history (including hashes) | `git log --oneline --all` |
+| go to some commit | `git checkout <commit hash>` |
+| create and go to new branch | `git checkout -b <branch-name>` or `git switch -c <branch-name>`|
+| OR: go to specific commit & make new branch in one step | `git checkout -b <branch name> <commit hash>` |
+| go back to main branch | `git checkout main` or `git switch main`|
+| merge changes from named commit with current branch | `git merge <branch_name>` |
+| create new commit that undoes all of the changes made in <commit> & apply it to the current branch | `git revert <commit>` |
+| remove <file> from the staging area but leave working directory unchanged | `git reset <file>` |
+
+## Connecting local to remote repo
+
+Go to [GitHub.com](https://github.com/) and create new repo. Then follow the instructions under **"…or push an existing repository from the command line"**:
+
+| Instruction | Command |
+|---------|-------------|
+| add origin | `git remote add origin https://github.com/<your_username>/<your_repo_name>.git` |
+| push changes | `git push -u origin main`
+
+## Working with branches on GitHub
+
+Go to [GitHub.com](https://github.com/) and create a new branch. Then:
+
+| Instruction | Command |
+|---------|-------------|
+| fetch the repo (doesn't merge) | `git fetch remote` |
+| check status | `git status` |
+| pull the repo (merge) | `git pull` |
+| see both remote and local branches | `git branch -a` |
+| create and go to new branch | `git checkout <branch-name>` |
+| push and create new remote branch | `git push --set-upstream origin <branch-name>` |
+
+
+## Forking, branching, and pull requests (using our repo as an example)
+
+Go to our class repo and create a fork. This creates your own server-side copy. Then:
+
+| Instruction | Command |
+|---------|-------------|
+| clone the repo | `git clone <URL>` | 
+| create new branch | `git checkout -b <branch-name>` or `git switch -c <branch-name>`|
+| stage changes | `git add *` |
+| create commit | `git commit -m “<some message>”` |
+| push commit |  `git push --set-upstream origin <branch-name>` |
+
+On [GitHub.com](https://github.com/), you can now create a pull request from your new branch to the 'official' repository. This needs to be approved by a repository maintainer.