My automatic garage door jams, what can I do to fix it? ?

I'm not very handy, my chain-powered genie garage door never used to but now sticks every time i use it. I literally have to give it a hand whenever i use it. What kind of steps could I do to help fix this problem? I live in NE Ohio which is a very cold/ area in winter if it makes a difference. I'm also not sure what kind of grease/lubrication i should use for it?