Show image if logged out - how?

[Hawkgirl]

I need to create a few conditional items based on user status.

One of the things I want to do is to be able to show an image on the Forum home page if the person viewing the page is unregistered/not logged in. (Right now our forums are totally hidden if unregistered/logged out, so visitors go there and they think there are no forums. I have a notice up, but I want to put a nice graphic there that says "Register to view forums!")

I am guessing this is php 101 - but I'm currently still in my prereqs.

Can you tell me what I need to write and where to put it? (Easy, right?)

After that I want to be able to display a Recent Threads widget - display titles of recent threads to unregistered/logged out users, but they have to login to read the content of the threads.

Thanks for your time ... I'll be paying it forward.