i search for forum thread that has my keywords and than post there with my links. is this a quality link building because the pages are at the same topic of my websites? thanks!
Sure, you can get a quality link like that. But, of what quality is the site you're posting your link to? Concentrate on getting "Authority" type links.. And you will see a huge difference in traffic. Maybe not right away, but you will.
You would be best served by not spamming forums but instead contributing to the community so that you get a legitimate backlink.
remember that the web is an ever changing landscape, so keep checking frequently and adding links whenever you can. Your old efforts will soon erode to newer sites, so keep up the work