See below

Method #1:

I always wait to carve our pumpkin until the day before Halloween.
That way we can enjoy a jack-o-lantern and use the pumpkin for
baking. It shouldnt spoil sitting out for a day. After all the seeds
are out of the pumpkin you can cook it by cutting it in half and
laying it flesh-side down on a baking sheet. Cook in a moderate oven
(about 325 degrees) for at least an hour. Check it frequently. When
the flesh is soft, scoop it away from the rind. Put it in a food
processor and pulse a few times to make it smooth. You can then use
it in recipes or freeze in bags for later use. I usually put about 2
cups in a bag. When using fresh (or frozen) pumpkin remember that it
is more watery than canned pumpkin. So cut down slightly on the
liquids in most recipes.”

Method #2:

To make the puree, cut a slice off the top of a fresh pumpkin with a
good sharp knife. Remove the seeds (see the recipe for toasting
them), peel, cut meat into big pieces and soak it 2 hours in very
cold water. Drain, place in a saucepan full of boiling water and let
boil covered until tender — it can take from 40-90 minutes,
depending on the quality of the pumpkin. Drain well, pass through a
sieve to puree, then use or freeze.