Best way to remove weeds and grow grass in the backyard?

we just bought a house and cant afford yard services at this point. Our backyard is filled with different weeds about 2-3 feet in height mostly about .15 of a acre size. can someone please give me an advice on the best and cheapest way to get rid of those weeds and plant grass. like, do we spray some weed killer and then pull out the weeds when they die then rake the soil and throw in grass seeds? or do we mow the weeds with a lawnmover then spray weed killer then rake the soil and throw grass seeds? were not really exactly sure what to do so any advice would really help. thanks.