How do I find logos or images such as for instance the profile picture or a lock or the search image. I want to change some of the images on my forum. I know how to change them but don't know where to find a site to get different images?

Just Google "Gif" and "Avatars" and you'll get plenty of free sites.

how can i insert a Header and a logo in my forum

Go to your Administrative Panel and click "Configuration and appearance of the message board" then put the URL of your logo/header in the text field that represents "Message board logo".
Then submit the changes and 'presto' you have a header.

Runawayhorses, your forum is absolutely gorgeous.  I just opened one and I'm afraid to mess with it.  It's dead boring, but I'm unclear on how large the logo should without setting the whole forum off kilter.  They really don't give you much info to go on.

Can you give me a clue as to how you got your forum to look so great?

Thanks!

Well thank you very much, thats always nice to hear!

My header is 570 wide by 173 high. But you can't really mess the forum up with the header size, I did lots of color adjustments in the Administration Panel too, not to mention making all the buttons and backgrounds myself. I used several image editing programs to make what I have.

The only advice I can give as far as the colors go is just try to envision what you want it to look like make the adjustments in the admin panel. It may take awhile to get it how you want, but now is the time for you to do it before you get all your new members coming in.

Good luck and thanks for the nice words!