Welcome to boas! They are great snakes!
Find out from the breeder which of the two anerythristic mutant genes he has in the double het ghost. Then get yourself an anerythristic or het anerythristic of that type. If you get the wrong anerythristic, you won't get any ghosts or anerythristics.
A ghost or DH ghost could also be used but would be more expensive.
Anerythristic X DH ghost -->
1/4 normal
1/4 anerythristic
1/4 salmon
1/4 ghost
Het anerythristic X DH ghost -->
3/8 normal (66% probability het anerythristic)
1/8 anerythristic
3/8 salmon (66% probability het anerythristic)
1/8 ghost
normal X DH ghost -->
1/2 salmon (50% probability het anerythristic)
1/2 normal (50% probability het anerythristic)
Disclaimer: fractions are the expectations. Actual results may differ more or less.
Hope that helps.
Paul Hollander