There's a pun in the title and original Super Mario Kart music from Mario Circuit here. Instead of driving, you'll be running around the track. Climb up the trees for a Super Bell. There are boost pads to speed you up, sometimes directly in the path of enemies. You'll have to attack to avoid taking damage. Dodge the Biddybuds and take the lower path with the donut lifts when the path splits. You'll find the first Green Star here. The top path has Piranha Plants. At the end of the track is a warp box. Go through it.
The warp box takes you to the top of a slide. You can slide into the Biddybuds to defeat them. At the bottom of the slide is the midpoint. Run up the hill and you'll see gaps with bouncy pads in them. Drop down into the second gap to reach the Mystery Box. You'll end up in a room with boost pads and a bunny. Use the boost pads to chase down the bunny for the second Green Star. Just be sure you don't end up on a boost pad in a corner. Jump to get out of it. When back on the main track, keep going and boost to a springboard. This will take you to some orange bouncy pads with the stamp. Slide down the slide and you'll find Piranha Plants at the bottom with the warp box. Ignore the warp box for now and climb up the wall behind it as a cat for the third Green Star.
The warp box takes you to another part of track. Run up the track, then slide to the flagpole.
The stamp is of a bunny.