Hi Linda

- you're going to need to lie on some kind of elevated surface so you can get your elbows down far enough for most chest exercises. An exercise ball makes an excellent bench and has the benefit of working your core too. People have also made do with coffee tables in a pinch.
There are two basic moves for chest (and endless variations): a chest press and a pec flye. They can be done on all kinds of elevations and with all kinds of equipment if you're in a gym. Since you're working out at home, you'll do fine with your DBs, though a weighted bar and resistance bands also work well for at-home workouts. The surface you lie on is going to have to be flat (unless you have a very funky coffee table!

)
Here are little videos of the basic exercises:
Dumbbell Flyes
Dumbbell Press
Typically I'd start a woman out with 5# on the flyes and 8 - 10# on the presses. Your 6# DBs may be a little light for presses and could be a little heavy for flyes. But try out your 6's and see how they feel. You want to shoot for 2 - 3 sets of 12 - 15 reps - smooth and controlled, without jerking. Definitely throw in some sets of pushups.
As for your arms, the basic exercise for biceps (front of your arms) is curls and a good one for triceps (back of the arm) is kickbacks.
Dumbbell Curls
Dumbbell Kickbacks
Again, the 6's may be too light for curls and too heavy for kickbacks, but play around and see how you do. It might be worth investing in some 8's, 10's, 12's, and 15's because you'll be progressing fairly quickly.
I hope this helps a bit - feel free to ask me to explain more if I muddled things up.