a "bump" occurs when a new post is added to the topic, even if its not from the poster. so, in a way, i just bumped this topic for you!
so really, to bump your post you can just type any reply to your post. for example, "added new pony", "updated list" or even just the simple "bump" all work. heck, even "laughing billy goats" could be a bump, but that might be considered spam...