If the location of the pain is your sit-bones, resist the temptation to get a "comfort" saddle. It may seem counter-intuitive, but by taking pressure off the sit-bones, they distribute it to even more sensitive soft tissue areas. Get your body used to being on the saddle by doing frequent short rides and see how it is after two to three weeks.
Bike shorts are also a good idea. The chamois in bike shorts adds a little padding but the main benefit is that by moving with your body, they prevent friction/chaffing as you naturally move around on the saddle.
If you bought your bike at a shop and they fit it for you, don't mess with the fit right away. If the bike hasn't been professionally fit, definitely visit your local bike shop and ask for a "basic" fit service (you don't need a "pro" fit yet). A basic fit shouldn't cost more than $50 and will ensure that your bike is set up so that it's reasonably comfortable and you're not at risk of injury.