OMG I was trying to reply to your comment on Just Desserts but instead i deleted it, I apologize for my fat fingers lol
anyway, you asked about buttercream, so this is the recipe i used: http://savorysweetlife.com/2011/04/chocolate-buttercream-frosting/
making frosting will never go right the first time, i can promise you, you have to keep trying haha. ummm i guess make sure you're using an electric mixer, because otherwise it's really just impossible, and also make sure to completely cream the butter. if you're adding powdered sugar and butter at the same time, it might get weird and pebbly, but just keep mixing because i promise it will eventually turn to frosting
i hope that helps haha (and that this isn't too awkward) but just let me know if you have more questions :)