W, Up arrow, move up. S, Down arrow, move down. D, Right arrow, shoot. Click one of the plant icons at the top to choose your plant. If you want to buy plant, click the icon of the plant, you want to buy and then click the buy button in the top right corner.
For some reason when you buy a new plant it'll say you don't have enough $$$, but if it unblurs then you've bought it.
