You main tools will probably be EQ and compression.
I'm assuming you only have the instrument as one wav file, not broken out into it's individual parts. If that's the case, what you essentially want to do is use the EQ to lower the dbs on the part of the beat that's clashing with your vocals. And in turn, cut some of the lower parts of your vocals (that u feel u don't need) that are clashing with the beat. This is called creating space.
In addition, you may want to make two copies of your voice.... compress one of them slightly, with a quick attack and a moderate release, maybe a 4:1 ratio or so, enough threshold to see maybe a 4-6db impact on your meter, nothing too crazy, raise the gain.... and keep the other copy dry so you keep the true essence of your vocal. See if that helps. Tweak the settings until you like what you hear.
To recap: 1) Fix the clash between beat & vocals w/ EQ.... 2) compress vocals to help them stand out.
Without the individual parts of the beat you can only do so much on your own. If you can get the beat tracked out then u can really go IN on your mix. But those quick adjustments above should help u get the ball rolling at least. It really takes a professional to do what ur trying to do and make it sound really really good. That will at least give you a halfway decent mix.