Clone platform.

`git clone git@github.com:diffblue/platform.git`

Make a new branch.

`git branch fix-copyright-notice`

Change to new branch.

`git checkout fix-copyright-notice`

Navigate to folder containing proxy guide.

 `cd docs/user/manual`

Open up the files in a text editor.

`atom .` if using atom.

Save changes.
cmd-s

Add the changes to git history.
`git add proxy-guide.md`

Commit the changes to git. And write message. Vim might open here to write press i when finished escape. And :wq to save.
 `git commit`

Push the branch.
`git push`

Read the error message. Run the command suggested.

Go to github open PR.
Assign reviewers.