Question
Small front lawn has been overcome by green mold --- how can I prepare and establish a new lawn ... the area is in the shade of a large oak tree.

Answer
Hi tony
You get this problem because of negligence. Don't worry. All you need to pulverize your soil. Add some  sulfur based anti fungal chemical in soil. You can easily get from lowes or home depot. Level the soil . As you told me your lawn is small , I suggest you to spread Sods there it will look nice instantly or you can use locally well adapted grass seeds according to your Zone. It will take 12-15 days to germinate. Apply some basal dose of fertilizers like NPK 14:14:14. That;s it

Aman