Havn't used Cubase for a fair old while, but if I remember right, when your in your sequencer window, if you look down the left hand side where all the track names are, in the bottom corner of the box with a tracks name and mute/solo/record buttons, theres a little + symbol, if you click that you'll get a box appear underneath for automation (may vary with different versions but its usualy similar layout). You can set the box to volume, and then simply draw in your volume changes. Make sure the tracks "Read" button is selected, otherwise it'll ignore the automation.
Another way would be set a track to "Write" automation, and just move the faders you want while playing the tune back, it'll record it in on its own then, but I find this way to be less accurate with a mouse, only really comes to good use with a control surface.
Dont really know about cubase but automating the volume of the desired track is the way to go about it. Or you could get abit more creative a put a filter and some distortion on the drums and filter it up, will sound alot more interesting, just an idea though lol