Well unfortunately you are pretty late. However, you could probably plant some cold crop transplants. At my garden center we sell lettuce plants this time of year, because the seeds needed to go down in late August and most people forget. Lettuce seeds do come up quickly and you can grow many kinds. Best advice, head over to a garden center, one staffed with experienced gardeners, and just ask. Your local guys will know how far along the planting calendar you are and can steer you in the right direction.
it is really too late to plant much of anything right now. Garlic is planted in the fall for harvest in July and you can also plant onion seed in the fall for summer harvest.
there are cold loving plants like spinach, radishes, lettuce, kale, arugula, pac choy and a few others that can be grown successfully in the fall and winter with protection (an unheated greenhouse/hoop house) but in order to harvest anything in the fall these things have to be started July through early September.
if you were an experience gardener I would say go ahead and plant some lettuce or radishes and put row cover or a low tunnel over top and see what you get in December/January
You should wait until spring when you compost is ready to use and spend this fall winter further prepping your garden area by laying down manure, getting the soil tested, looking at seed catalogs which will help you plan what you want to grow next year.
BTW, Pumpkins are not grown this time of year-they are sold this time of year but have been harvested many weeks ago. Pumpkins and other squash are grown in the summer