Put an @LABEL (You can replace "LABEL" with whatever you want) and then you can use the GOTO @LABEL command to send the code back that point. Something like this:
@LOOP
PRINT "TEST"
GOTO @LOOP
The label thing works, but it's a very bad habit if you plan on going into other programming languages (trust me, I had to break that habit). Using something like WHILE would be better.
WHILE TRUE
PRINT "TEST"
WEND