Hi CarliesHero. Welcome to SitePoint.
There are a lot of CMSs out there, both free and commercial, that can do this. Take an example like Drupal. It will have addons like ecommerce and a forum that you can build in. I don't use Drupal myself, but rather ExpressionEgnine, which costs a bit (around $300) but it's lovely to use and has a first-party forum addon and some excellent 3rd party ecommerce addons (the best being CartThrob). That's a very design-friendly option for you, as you don't need to be a programming aficionado to work with it and its code is very clean.
Another widely used free option would be WordPress, which has options for carts and forums. Probably not as easy to use, but WordPress has a lot of support.