Best way is to ask someone to help you. Otherwise you learn how to swing them up into position starting from a sitting upright position.
edit: here I found a video, didn't watch it all or listen to the audio but around the one minute mark he shows you how to get them up
http://www.youtube.com/watch?v=622ku8i0M14
I use my knees to sort of propel them into position, as I've seen others do. Still unsuccessful at times (the lifts that gave me trouble before are dumbell flys and dumbell military presses). Gonna watch the vid right now