Can anyone who has experience in Microsoft Access help me?

[GdaTyler]

I really need help with an IF function. It's driving me nuts. The question is:

Perform a query to deduct a ten percent discount on total payments made by persons who made bookings on the Asian tour. Name this query FurtherDiscount.  

So I made a query with the columns: Name, Total Payment, Tour Specified

It has 4 tours: Asian, European, African, Caribbean

What I want to do is make an if function in my query that says: If Tour Specified=Asian then multiply the Total Payment field by 90%

Damn, can someone help me? Your help would be greatly appreciated!