First order of business, remember that you log in to my site with the same login & password you use to log in to playmyth.net. Joe (Blue of e.i.) was kind enough to work with me to build an interface to their system. Do not ask me about forgotten passwords, direct all such inquiries to playmyth.net.
Now, you may notice as you're browsing through the site that your URL often has an input variable "sid=" attached to it. Once you've logged in it has a scary looking string of characters after it too.
This is called your session key, and it's used to identify you. When you log in, you are assigned a unique session key that is carried around as you browse the site, so that all the scripts know who you are. As long as sid=[your key] remains in the URL and your IP doesn't change, you are logged in. I also automatically send you a cookie that contains another special key. If your browser is configured correctly, and you accept the cookie, you'll be logged in automatically when you use that computer, up to 6 months after you log in.
If you're using a public computer or are concerned about people seeing your cookie, you should log out when you finish browsing. Every key you've ever created will cease to function, and the cookie on your current machine will be deleted. Your cookies on all the other machines you browse from will all be useless. Once you log out, it's not possible to impersonate you without supplying your pm.net password.
There is a slight continuity problem with the forum. Since I use WebBBS I can't exactly change all the links to include the key, so if the cookie doesn't work for you and you want to stay logged in, browse the forum in a new window, or use a bookmark to go back to the main site.