There are several recipes you can follow. I got mine off this website:How to Cook your Pumpkin.
1) Clean the outside of the pumpkin.
2) Cut pumpkin into pieces (I did 4).
3) Carve and scrape out the seeds and strings.
4) Put in covered dish and bake in the oven for about an hour.
After one hour, the peel came right off and it was pretty mushed/pureed already. I plopped it into a plastic container and stored it in my fridge for making. It yielded about 4 cups, enough for 2 recipes of pumpkin chocolate chip cake! Delicious!
If you are wondering about pumpkin chocolate chip muffins/cake, here is the recipe!