I put diesel in my engine, help!!

You didn't smell the diesel when mixing the two together? Wow.
Sounds like its time to purchase a four stroke... never mind... I guess it could have gotten poured into that tank too.

No harm done...
Drain your tank and float bowl.
Install a fresh plug, and have a few extra handy.
Kick start it and go from there.
Ride it out.
 
It's not as bad as putting gasoline into a diesel so that's a positive. Do as Joe suggested and you'll be fine.