These forums are a good place to ask questions. But before you do try browsing through and searching these forums and read what has already been discussed. You will find that many question you have/will have have been discussed. Plus you will learn many other things (answers to questions you didn't know to ask about).
Also, click on "Robot Tutorials" in the upper right corner of this web page and read the many articles.
Wheel RPM to linear distance traveled is very simple math (compared to other math needed for robot). So I will try to lead you to find the answer with questions (you will learn it this way).
What is the circumference of the wheel?
Then, how far will the bot travel when the wheel makes one revolution?
Hint: convert all occurrences of time to seconds and all linear measurements to inches.
ie. convert RPM to RPseconds before calculations
What does RPM mean? Hint: Express this as in math as revolutions divided by minutes
Now, the linear distance in one revolution is the circumference of the wheel. So 1 rev = 1 circumference.
Is this enough for you to solve the problem?