Hi Dave,
Read the MaxIm help files, really, it won't take more than an hour to go over once., specifically:
http://www.cyanogen.com/help/maximdl...ing_Images.htm
http://www.cyanogen.com/help/maximdl...OC_COMBINE.htm
these online links provide exactly what is in the printed manual and the built-in help file, BTW click on the "Show" link to bring up the table of contents. Then try it with your images. If in doubt leave the default settings. Once your image is stacked, then stretch (Stretch dialog for gamma/log/linear or DDP dialog).
EB