I konow forums are websites too, but someone told me that Google doesn't like links from forums as much as regular pages. Is this true?
Links are not created equal. If you have 1000 total links and 400 are from one forum then those links will not carry the same weight compared to each link being from a distinctly different domain. Also, link relevancy is important. A link to a dog training site from an seo forum is off topic. Many forum's do not use h1 headers and the title is the initial subject of the first post. So, again, the "page content relevancy" (title, heading, content) to the link is important. Get a link about dog training on a page related to dog training and your link is worth more than off topic forum posts. But, they are not worthless.... Are your links junk?