-Guild Banners-
Those nifty little banners that go in the top right hand corner of your guild pages (and beside your guild's name in the search list). I'm gonna tell you all about them.
Technical Stuff
Measurements
Guild banners should be 200 pixels wide and 40 pixels high. This measurement is usually shortened to "200x40" when typed out.
File Type
You can use .GIF, .JPG, or .PNG
File Size
As far as I know they can be any size. Though I would not recommend taking extreme advantage of this as larger file sizes will cause the page and image to load slower... especially for those who use dial-up. This could possibly discourage potential members!
Animated Banners
You may have animated banners.
Randomized Banners
You may randomize your banners as well. I'm not going to go into how to randomize them, but there are PLENTY of tutorials floating around on Gaia, particularly in here. So you should be able to find out how rather easily.
Hosting Your Banner
This is your responsibility. You must find a host to upload your banner to. You can use your own webspace (if you have any), or there are plenty of free hosts on the internet that you can use. www.photobucket.com and www.tinypic.com are a couple you can use, but I'm not going to list them all here since this info is covered all over Gaia.
Just make sure your host allows hotlinking (ie: linking to just an image). Also be sure to check what their bandwidth limits are, what their content rules are, what kinds of file types they allow, and how reliable they are.
Once you banner is hosted, you'll need to go to your Moderator Panel. Then to "Edit guild settings". Then all you will need to do is copy and paste the banner's URL (that's web address) into the space you see marked "Banner". Do NOT include any