it's really easy to make a poll!! go to the link below to see how. you can try it at a post on your own LJ first, if you're afraid of messing up. the only thing you need to remember is that you can only make a poll before you post up your entry. you can't edit the entry and try to add a poll. it will only work before you post up the entry. also, you can't edit the poll after you post it up. so be careful and make sure you don't make any typos or something before you post up the poll. lol.
http://www.livejournal.com/support/faq/69.html