How to display a message with IF Statements?

I'm making an order form for a basketball store and I want a message that displays "Send free Keychain" for grand totals (Cell D20) over $100.00. Somebody told me I should use these functions to get this to look right:

AND
IF
NOT
OR

How should I do this?

Note: Ignore any errors. I'll fix those myself.

I want this to go into cell D22