I have problem in setting UPS Shipping rates

[webrule]

Hello,

i am new user of joomla 1.5 or VirtueMart 1.1.0. i have to set shipping rates can any one guide me how to set shipping rates i am using UPS but according to products
mean Product1 having $20 shipping cost product2 is $30 mean i have fixed shipping cost according to product.

but in shipping rates its asking for product weight etc how can i simply set the standard shipping rate for a product

please guide me

thanks