It's pretty much the same thing.
SPSET 0 the definition number,1 the sprite that you want. then SPOFS 0 def number,x,y
IF BUTTON==#left THEN X=X-1. And then x+1 for right.
This won't fix what you're talking about, though I advise that you use REPEAT or WHILE loops instead of GOTO. GOTO will cause you many problems in the future.
This screenshot shows code to move a sprite using the X Y A B buttons. Change "AND" in the button() test statements to "==" if you don't want to allow diagonal movement.