Well, it's never hugely comfortable when you first start--your body isn't used to having that sort of stress on that area for very long.
A couple things to do:
1. Have your bike shop help you with your saddle position and general position on the bike. Odds are you will feel like you're sitting way too high up at first, bt you quickly get used to it. You reap huge benefits in butt comfort, efficiency, and knee health from these changes.
2. Get a pair of cycling shorts. If you don't like the lycra look, there are plenty of baggy shorts on the market which have a lycra liner covered by a nylon shell that looks like a regular pair of shorts. These give you several benefits as well: A chamois pad that helps as far as pressure, the tight fit of the inner liner helps prevent chafing, and they're just generally a lot more comfortable.