You should remove PRINT XSCREEN, since XSCREEN is an instruction (and has no return values). Trying to print an instruction with no return values just prints 0.
Also, you should remove all those PRINT "" since they serve absolutely no purpose.
I learned a lot from this game's instruction, Petit Professor, and from Miiverse, mostly from Oscar. xP
You don't really need all those prints. You can just overlap your text with just spaces, like so:
(? is another way to Print)
Locate 20,15 ?"Hello there!"
Wait 100
Locate 20,15 ?" "