So I just want to preface this by saying I am a complete and utter n00b and basically know next to nothing about Basic Ti or otherwise.

I don't have a link cable for my TI-83 Plus so I am trying to copy this tetris program line by line into the calculator and I keep finding tildes, which is this symbol (~), but I don't believe the calculator has that symbol.
For a bit of context, I usually find it in expressions like this:

If L=2:Then
1->D:0->E
2->F:0->G
~1->H:0->I

So again, I'm the Jon Snow of TI Basic and basically how do i deal with this (~) that keeps popping up?

jsTIfied uses tildes to represent negative. ~1 is equivalent to negative 1. Hope that helps!

Ah there you go, that makes sense. Thank you!

For the actual tilde symbol, you would type |~ as well, instead of just the tilde.