If using the Midi loops , find a groove close to what you feel and just loop it for a whole song.
Record your Music around that.Once that process is done you will know i want some fills here and a stops there.Or the kicks can be played with.
Depends on the words and style but sometimes fills can get in the way just as much as be crucial when needed.

One other thing is to drag the Intro, verse, chorus, bridge pieces of the chosen groove into your song and just nut out a quick approximation,
using those building blocks if they work, you will have a more advanced version of the first way suggested.

Also the velocity button affect grooves from the browser so you can try lowering it to the left and dnd your midi file and then on the same midi increase the velocity and dnd again to build dynamics.
I find this works best when lowering and only bring back up to original setting as increasing can bring up ghost notes and subtle things and be un natural.

Hope any of that helps.