http://forum.imgburn.com/index.php?showtopic=61 <- please follow this guide, and if you have any doubts, feel free to ask
By the way, to get the best burn, check if your burner has the latest firmware (you can do this with ImgBurn by going to Tools- > Drive -> Check for Firmware Update) and use Verbatim DVD+R DL 2.4x MKM-001-00 Made in Singapore media