Click Analyze -->Pinpoint Astrometry (this opens a new window)
Image Parameters
Set pixel scale to 0.76 for X and Y
RA and DEC should be entered if not automatically from header
Catalog Setup
Reference Catalog set to USNO B1.0 (net)
Make sure Search Outward Spiral is UNCHECKED
You can adjust the mgnitude range to allow more of less stars to be used
Click Process and you should have a solution in a minute or two. If it fails or takes too long, most likely you have too few or too many stars beings used so adjust the magnitude range and try again. The WCS will be entered into the header