need help with cake decorating..I just cant seem to get it?

[Kayce]

ive just started trying the whole cake decorating and im not having any luck.I bought the course 1 book and the student kit at hobby lobby.I can make a rose but it looks like a 5 year old did it.I know im not going to be great right off the bat.Every time i try to do it...it makes my hand hurt from squeezing the bag.What am i doing wrong?Does anybody have any advice for me?I really want to do it but it seems like no matter how hard i try it doesn't work.I cant get my icing right its either to soft are cracking.Ive watched videos on youtube but its still not helping,