Martin27, On many forums that would be perfectly acceptable. Even those that don't allow advertising, generally allow members to include a link to their own website in the 'signature' section of the post. At least, if that's where it is everyone knows where the link goes to.
However, this site does not have signatures on posts. (It doesn't even allow avatars.) In that case any link provided is assumed to be in support of the answer being given. You therefore understand the resentment when people find it is of no help in that respect.. Please understand Martin27, that (currently) on this site, self advertising is considered a no-no.