To answer this question the best way possible you need to understand two concepts -Indexing & Committing.
Indexing: After you have created a new file or made changes to it, you need to move it from the working directory to the index.
For that, we use git add <file name>
Or, git add -A (-A means add all files that are in the working directory)
Committing: After you have added them to the index, it is ready to get committed.
For that, we use git commit -m “message”
Or, git commit -a -m “message” (-a means add all modified files in the index)