Attach the wheel, put the chain on, tension the whole assembly, fit your DIY unicycle saddle and you're off! Be safe!!
Step 4: Welding in the top part of the frame
The top part of the frame is the bottom bracket with the seat tube from the original bike still welded to it. Now at this moment it's critical to align the top of the seat tube, the bottom bracket and the axle of the wheel on a single line BEFORE welding.