How to touch up scratches and scrapes in stained furniture?

I have a a rose??? stained wooden couch sort of like a futon, that has big scrapes and scratches on it from the movers. The rest of the wood looks great but the sides of the arm rests are really scratched up. How can I restain or touch up the parts that look terrible without having to redo the whole couch? Do I have to sand down the area first? I am not very handy at this and have never tried so I am afraid of making things worse. Thanks for any advice.