Probably not, to be honest. At least not directly. Photoimpact is a fine program and it's capable of many cool effects. Unfortunately, as you've already learned, Photoshop is THE most popular graphics app ever created. It's a professional-grade application that offers unparalleled control in the hands of an experienced user (I've been using it professionally for at least 16+ years).
Now, that doesn't mean that you cannot accomplish great things with the app you have. In fact, whatever you do, don't rush out and buy Photoshop -- it's expensive and overkill for your current needs or skill level.
The first thing I can suggest you do is actually MAKE something with Photoimpact. Make a single game tile and see how it goes. You can learn a LOT by just doing something simple.
Download a ground texture and start from there. Since these are for personal use, just go to google and do an image search on "ground textures" and see what you find. You want larger images (1024 x 768 & up) to work with, as they'll yield the best results.
Also, go to Amazon.com and do a search for PhotoImpact under books. There are several books dealing with older versions of your app -- even though they're not the exact version you have, they really should help you get started (and they're cheap).
Finally, you might try visiting renderosity.com, which is an artists community for amatuers and pros alike. Start hanging around there and you'll quickly soak up lots of knowledge and ideas for your projects.
Good luck and happy bitmapping!
