10 Inch Reflector Telescope Dobsonian Telescope?

Dobsonian Telescope? - 10 inch reflector telescope

We have recently purhcased Mount Dobsonian telescope of 10 inches. The first opportunity to use and last night had some difficulties, as the moon. It is quite possible that we were wrong in the eye (the mind, we tried, all eyes - 6mm, 9mm, 15mm and 25mm). What we do wrong?
Thanks