How to take lunar photographs with digital camera ...

Many different ways. Attach the camera to the top of the scope. Use whatever sized lens you'd like, use the "B" exposure and fire away. 

You can also (depending on the telescope) buy various converters. One would be a Film Plain converter, where the image from the telescope is projected directly onto the film/sensor surface. Another is the Eyepiece Projection Method that allows you to use the magnification from you eye pieces and project them onto the sensor. 

I'd suggest doing a google on Astrophotography for vastly more in depth data. 

if you are using an ordinary lens, i myself, i use a 105mm kit lens, i shoot the moon with the highest reolution that your camera can do., so when you crop it out., it will still look sharp. I learned that when shooting bolts and gate valves , i shoot it big so the bolts looks sharp.