How To Show/Block specific content (Ads) for guests/members or certain users

O thank you a lot, it's just what I need.
What am I doing this for? Mmm because this will make guests register on the forum. I don't want to make everyone register, so everybody can ask for a piece of advice, but if you need a link that is in the post, please register.

I think when you share links, you give some kind of impression to search engines. Because they like the sites which link to other (or at least they should definitely like it). And it is good to share links to everybody, for example I like browsing web anonymously without registration, and it would enrages me if I'd need to spent a lot of time just for viewing one link.

But if it works for you, you're welcome :-)