Of course you can. It's just that photoshop makes everything easier if your a pro or intermediate, and impossible if you're a n00b. If you can figure it out then you'll find it to be easy. paintshop should work fine though!
Try downloading a couple of templates from the following site - http://www.oswd.org/ - It's open source web designs... you can play around with the html code to see how the templates are put together etc. That is how I taught myself... just play around - you'll get it!