I don't think I'd classify that as easy for a beginner. It involves fair isle knitting, shaping and working with charts. It's not impossible, but you'll need to be patient with yourself as you learn.
How you join a new color depends on what you're doing. For fair isle you don't knit with them together, but you are using both yarns and carrying them along. I carry one color in each hand and knit both continental and English at the same time. Some people carry them both in one hand.