Animal Crossing New Horizons is set on a deserted island and as such, you'll start off in a tent. This will tide you over for the first portion of the game, but you'll eventually want to get yourself a house. Here's how to get one.
How to Get a House
If you want to upgrade to a house you'll need to speak to Resident's Services. You can speak to Tom Nook, where he'll offer you a loan on a house. There's no deadline to pay it off and it's interest free.
How Much Does a House Cost?
Moving from a tent to a house will cost you a fair bit. The loan Tom Nook offers is for 98,000 Bells. This is obviously a large amount of Bells, though the extra space seems worth it for the additional storage options you'll get.
Extensions and Remodelling
Once you have your first house, there are options to add to it. Tom Nook will offer packages on extensions and remodelling, significantly increasing your space. It'll cost you Bells of course. You can add new rooms, giving you more options for decorating.