Hello! New to PbP, some RPG experience
 

Hello! As I mentioned in the title, I'm new to play-by-post games, but I've been playing RPGs for the past two or three years and Myth Weavers seems like a really cool place to play more! Recently, I've had my interest sparked in older versions of D&D and other retro-clones. I started with D&D 3.5 and I've played others such as Savage Worlds and Stars Without Number.

Welcome! Older D&D and retro-clones are gaining in popularity here, and another one pops up now and then. If you keep your eye out, it shouldn't take long for another one to start up!

Otherwise, there are plenty of 3.5/4e games to go around!

I'm currently advertising a game that utilizes the Astonishing Swordsmen & Sorcerers of Hyperborea rules, which are a simulacrum of older D&D editions (especially AD&D).

Check it out http://www.myth-weavers.com/game.php?g=13455

That sounds very interesting. How would I go about "joining" your game? Should I just post in the advertisement?

You should go to the Character Creation thread in the Game Forum. There are currently four prospective players, a Paladin, Magician, Ranger, and Bard. I wouldn't be opposed to including more characters. Feel free to roll one up.