I just started a new store (see my signature for link). It was set up on IPage with a few simple steps. The problem is that I don't know how to calculate shipping costs. How is that done for UPS? Also how about sales taxes? AFAIK USA does not have sales taxes on web products, but I could easily be wrong about that. Am I supposed to collect sales taxes?

You will need to collect and remit sales tax on sales made in your own state.

yeah, you will have to do that

I use OSCommerce for my sites and have FedEx shipping available. FedEx has an API that gets installed into oscommerce and gives me shipping charges based on the weight (in pounds) of what I sell.

Tax calcs are also built in. I charge tax in my home state only.

They have many plugins. It might be best to do a flat rate,

Flat Rate shipping causes 1) customers to go elsewhere because your rates are too high, or 2) you lose money because your rates are too low. At best, flat rate shipping is a gamble.

Better to get an actual shipping charge from FedEx, UPS, or the Post Office. The FedEx module I use is called "fedex1.php". It's provided by FedEx. It gets a shipping charge directly from Fedex and presents it to me. I just add it to the customers order.

yeah ofcourse,you need to collect that.
and for the shipping charges if you dont get it from the customer,then you have to pay it