Hi,
i want to use yaf in my asp .net mvc site with providing functionality: when user create account on my web site he doesn't have to create it on forum separately, when user log in on my web site hes logged on forum. Is this possibly and what re best ways to do that?

When user is in a common .ASP Role which is included in YAF - you can see it on the groups page he included in YAF tables automatically after his first login. If it's not included you should add it to YAF.