Upper body workout help please ?

In a way where I have a lean look with some muscle definition. My legs are sorted, as I do interval training on elliptical and stationary and cycle so my thighs are pretty solid, but I do little on my upper body. I have been toying with the idea of getting some 3kg and 4kg dumbells and doing some bodyweight exercises but need a site or a book that will give me the best exercises to do with these for my waist, arms and stomach.
I do not wish to lift heavy, too much of a strain on my body, personally.