In order to record the changes you have made to the lesson-1.md files, you need to first add them to the staging area, and then to commit the staged changes.
Use the following command in a terminal:
git add lesson-1.md
Then, use the following command:
git commit
Which will ask you for a commit message: a short summary of your changes. You can provide a single line like “Fixing typos in lesson-1.md”.