Now you have a branch that is specific to your CR. You can start making changes that you want your CR to make.
Ensure you are in your CR branch
If you have just completed step 4 then you will already be in the correct branch.
If you are coming back to the Forge at some point afterwards, then by default you will be taken to the "master" branch instead. You will need to navigate to your CR branch by checking the drop-down near the top left of the page.
Make some changes
To make changes, simply click on a file that you'd like to make changes to. You will be presented with the current version of the file. You can edit it by clicking on the "Edit" button near the top right of the page. Doing so will enter the editor, where you can make whatever changes you wish.
There are many other ways of making changes to a file. You could use
the Web IDE, or making a local clone of the repository on your computer and use the
development tool of your choice. If you are comfortable doing that - go for it!