first time knitting...

[tabbymarie]

i watched the long tail cast-on video atleast 50 times now and i just cannot get it right. i go under the left thumb loop and go over under the top one as it says to and when i pull it doesn't go on, it just has the yarn wrapped around the needle as if i simply wrapped it around. i've been trying to do it for 4 hours now. any suggestions? i am copying what the lady in the video is doing but it just won't work for me.