Your first and primary method for feeding your growing settlement is to get meat, and to get it you must hunt various animals on the map. To do this, you must first have a settler with a high or decent enough marksman skill of at least eight.
After that, you will need to set their job to priority one for hunt and then mark some animals for them to hunt on the game map.
To do this find the bow and arrow key on the bottom left of your screen and click it or hit m. When you have done that, scan the map for animals such as deer or rabbits as shown above and highlight them.
Related: How to cook food in Going Medieval
Once highlighted, your hunter will run over and try to hunt the animals, but for them to be effective at hunting them, you must equip them with a bow.
That said, you should have at least one bow over at your stockpile when you start the game, so go over there now and right-click the bow with your hunter selected.
After a while, you should have plenty of raw meat rolling in, but you can't eat raw meat, so you will need to cook it. To cook your meat, you will need to build a campfire and butcher's table and then start a production tab in both stations.