Very Easy
Just take the horn button out with a screw driver then undo the nut inside with a 19mm socket pull the wheel off (it mey need some force) once its off make sure the cable for the horn is at the top, And make sure your wheel has the hole at the top too.
Then put the wheel back on Straight.
Ok there is a way dot on the bolt and one on the wheel so its easy to centre it.
My problem was that the wheel was not a hicas one so i brought a aftermarket wheel and hicas adaptor.
Hope this helps
Dan