That's the shortcut method. If you want to hunt and peck, click your windows icon and either go through the menus or just type "character map" in the search bar. Once you get into the character map popup, select "Cambria math" from the drop down menu and find your symbol. Click on that and copy/paste in the BB code editor. Actually, I think it works in the rich text editor now too, but if I recall we had to switch editors (wrench in upper right) to make it work in earlier versions of the software. The degree character is U+00B0 and there's a note on the message bar at the bottom of the popup that shows the shortcut "ALT+0176". Just remember the shortcut and you won't have to go through all of that. I usually just put a comma or asterisk 'cuz I'm lazy.