if you want squash top 3 commits from your head,
Use this command,
git rebase -i HEAD~3
Here the tilde ~ symbol with 3 pick the top latest three commits and it will pop up in an interactive shell where you can select the top commit and squash other two commits into one by entering s, it means squash.
If your commit is not appearing then do git log and see, if not then
git add files
git commit -m 'your commit'