It would be kinda like this
@mainloop
Wait 1
spset 0,1
spofs 0,x,y
Gosub @Move
Goto @mainloop
@move
B=Button()
If b==1 then y=y+1
If b==2 then y=y-1
If b==4 then x=x+1
If b==8 then y=y-1
Return
You have to toy with it, but after you set it right then it will move up with the up button etc