knitting question

[cookiezs.livejournal.com]

i have a question about knitting..

i forgot how to cast on and i had someone show me how again, but i know that when you do it you're supposed to use the tail (the smaller piece) and not the actual yarn (the tail should get smaller) and somehow when i'm doing it the tail is not getting smaller because i am somehow using the yarn. do i NEED to fix this or will the scarf be ok if i dont change it? and if i need to fix it how do i cast on? thank you!

i hope this makes sense!