Dear Rufaro, here is a video on how to make your own solar cooker. You can do it first from cardboard and then when you have made one or two you can try using wood.
There is also an entire rocket stove forum here on permies - rocket stoves are designs that allow you to use less wood, even twigs and brush rather than logs. A heat preserver (Wonderbag) is also a piece of equipment that meets speedy uptake in the communities I have worked in.
You can also go really old school and heap some thick rocks in a hollow and line with foil. They will get hot enough to fry an egg in, don't worry.
I am sad for the trees and the climate, but more than that it seems only a matter of time before they are all gone. Might as well start working on the solar cookers while you still have time because it is the inevitable option. There will be plenty of sun this summer.