To get a house you first need to place a tent. To buy a tent you need money. To get money as a new player it is easiest to catch fish. The whitefish in the lake just NW of the main vendor, Sgt. Lake, sell for 150 each, so just catching a few will get you a tent. The best place to catch those fish on that lake is a small spot where you can reach them on the north side of the lake. Catch the fish. sell them to the fish vendor at sgt lake who will get you the best price for them. Sell other stuff you loot to the vending machine on the far right.
Then find a good spot to place your tent, which is an empty spot away from other houses, tents, or trees, which will block it. Alot of new player die trying to find a good spot and then lose their tent when they die (when you die you lose everything on you except your money). Therefore, find a good empty place first, saved your money, and then get stocked on some cooked food for health if you need it.
Then buy the tent, and make a safe quick trip and carefully place it. Enter it to claim it as your respawn point. If needed, as you plan your route to your location, you might even buy a boat trip there just to be safe if that is faster and avoids players. It is better to spend money on a boat than to lose your first tent.
Once you have your tent you need a crafting bench placed inside to upgrade to a house. These are expensive from the red vendor, like 7000, so a better way to get one is to loot the warehouses you see around the map for one, or check the green vendor if there are used ones for sale. On my server the green vendor had several for only 700. Place the crafting bench in your tent.
Then you need to gather 100 wood from trees with an axe or chainsaw. Axes can be found from loot chests or from the green vendor for around 700, and chainsaws from loot chests but 3500 from the green vendor. Axes gather wood slowly, but the chainsaws are way too expensive. If you are lucky you can loot a chainsaw, but your best bet is to run around and ask to borrow one from another player. Most players have several they are storing. In the meantime while you look for a chainsaw you can buy storage chests (about 700 each) and place these in your tent because you will always be in need of more of those. Once you get an axe or chainsaw chop down 100 logs and place them in the crafting bench using the ‘deposit’ button on the crafting bench. You can do this in multiple play sessions as it does take a while. Once you have all 100 logs in the crafting bench click the ‘upgrade’ button that appears and your tent will then turn into a house!
Other tips - You should consider looking at the map of the island on the discord and explore a bit to see different house locations, and learn where the boats go. You should also place at least two fireplaces (the small black ones) that you buy from the vendor inside the tent so you can regen your health. Fireplaces are like free food because they regenerate you, and the more the better as this effect stacks. The storage crates can stack in your tent as well to save space. Do not place anything outside your tent as it can just get easily picked up and stolen. Once you have a house players have to destroy things outside your house to steal the bag that will drop when they destroy it. The next goal after a house is to upgrade your house and get turrets to protect your house from raiders. You can also do the hunting, fishing, and gathering quests, which allow you to sell things back at higher prices to special vendors, and these also challenge you to explore the whole map. Make friends too!