It is quite likely overexposed. For the Moon, use an exposure that is just like what you'd use to shoot a daylight landscape (you are, after all, photographing reflected sunlight that's just as bright as what you see in daylight, and at about the same distance from the Sun).
You should also use a low ISO setting.
That will ensure you're not way overexposing the Moon. Once you can see the Moon more clearly in your viewfinder, you should be better able to judge focus.
With a reflector, you'll often find the camera won't go far enough toward the mirror to achieve focus. Some reflectors include a 2" focuser with a barrel that is thread for a T-adapter, so you can "lower" your camera closer to the reflector's body.
Another way to handle the problem (should you have it) is to move the focal point further from the body of the telescope. The easy way to do this is to use a barlow attached to the camera adapter. That method also increases the focal length of the scope so much that the field of view you can photograph is much smaller.
It is more difficult, and requires modifying the telescope, but you can also move the focal point further out by moving the primary mirror of the telescope toward the focuser. This involves removing the mirror and its cell and drilling a new set of mounting holes for it, an inch or two further than the current holes toward the front end of the scope.
The universe is not only stranger than we imagine, it's stranger than we CAN imagine. --- JBS Haldane
Come visit me at Comanche Springs Astronomy Campus (we're on Google Maps) in Texas.