Git commit in terminal opens VIM, but can't get back to terminal
To save your work and exit press Esc and then :wq (w for write and q for quit).
Alternatively, you could both save and exit by pressing Esc and then :x
To set another editor run export EDITOR=myFavoriteEdioron your terminal, where myFavoriteEdior can be vi, gedit, subl(for sublime) etc.
not really the answer to the VIM problem but you could use the command line to also enter the commit message:
git commit -m "This is the first commit"