Simple calculator

I'm not sure if this is too simple or too complicated for Creator, but I can't find an example anywhere....

I am trying to make a simple calculator for my web site. It's easy to do in excel, but it doesn't translate if I import it into Creator, and I can't figure out how to write the script myself. (I am not a programmer!)

For example, here's a simple sales commission calculator:

User enters gross sales ($x) and commission rate (y%) and the commission is displayed: Forumla $x * y% = $z

Ideally this would display instantly, and not require going to a new page or even a refresh. I do not need to save the data anywhere either, so no database is required.

This is the simplest version. I might extend it thusly:
- enter number of sales and individual sale value to calculate gross sales
- add bonus levels to commission (if gross sales less than A, bonus = 0. If gross sales exceed B, add bonus of $C to commission..... etc)

Any assistance would be fantastic!

Cass