"If/than" statements

Excel

Trying to learn- this is probably pretty simple! I am attempting an "If/than" statement in conditional formatting. The attached document is ran from a report in a medical database. Goals: 

- If column R (route) has a cell = 0 I want that row's column T to automatically populate the number "2". 

- If column R has a number in it I want that row in column T to remain blank.