|If you read the Help files, then you know that an IF statement needs a logical_test, a value_if_true and a value_if_false, each separted by a comma.|
What is your logical_test?
What is your value_if_true?
What is your value_if_false?
Hint: One of them is missing from your post.
Once you have all of the pieces, I think the Excel help files are pretty clear on how to construct the formula. The Help files give numerous examples, some as simple as yours and others that are relatively complicated.
Tell us where you are having your problems and we'll see what we can offer. Try to build your formula, and if doesn't work, post it here and we'll take a look at it.