I am like Tiberius.... I have a Google Icon which has several Google apps within that icon button.  

If you don't see that icon your phone screen..... type "Gmail" in your search bar.  See if Gmail comes up.  It might be that it does not show because you have not used Gmail in your phone yet..

Go into Play Store. In the search bar, type in "Gmail". It should come up. If you have Gmail already in your phone, it will show "Update"; if you don't have it already installed, it should direct you to install it.