No drummer?
You have no drummer so you have to record your song along to a rhythm unit? So it sounds, crap...like a rhythm unit?
So using the sampled drum settings on your midi keyboard you 'track' each of the rhythm unit 'drums' in turn recording your manual drums onto a seaprate track - kick drum, snare, etc.
You can then add in some variation on rolls when you become more accomplished (takes a bit of practice) and end up with a recorded kit you can mix individualy. Of course you then mix out the rhythm unit. For hi hats try leaving in the original rhythm unit hihats but rtemove all the bass an mids and boost the hi's, virtualy eliminates the 'drums' just leaving the 'hihat' sound.
For the icing on the cake overdub maracass and or tambourine and you'll end up with something that sounds like you had a real drummer there (albeit a basic one!).
Why not just use midi you ask? Well this way puts in little imperfections which add the 'human touch' and don't sound so much like a mcahine, whilst keeping 99.9% perfect time!
Works for me anyway!