General workflow is as follows:
You clone the Git repository as a working copy.
You modify the working copy by adding/editing files.
If necessary, you also update the working copy by taking other developer's changes.
You review the changes before commit.
You commit changes. If everything is fine, then you push the changes to the repository.
After committing, if you realize something is wrong, then you correct the last commit and push the changes to the repository.
Shown below is the pictorial representation of the work-flow.