Happy to have you here, sorry you got your bunfrom a pet store. Selling buns at 6 weeks is really toosoon,but that is pet stores for you. Responsible breedersonly wean their kits at six weeks and don't sell until 8 weeks, but petstores get their stock from "rabbit raisers" mostly, and unfortunatly,because they are weaned to early and sold at 6 weeks, many passaway.
Having said that. Get a good quality pellet food from a feedstore. Blue Seal, Purina, Agway and many others arefine. Protein should be 16%. Feed feed your bununtil 6 months old. Then weigh him and feed one ounce ofpellets for each pound of body weight. You can also get a boxof Old Fashioned Oats in the grocery store, any brand will do, so longas it is not Quick Oats. These can also be freefed. Timothy hay is a must. It keeps everythingmoving along inside your bun. It can be bought in cube form,great for one bun and keeps the mess of hay away. Water canbe from a bottle or crock. Fresh water should always beavailable.
You will need a cage with a drop pan underneath so that the bunny willnot be sitting in his urine and droppings. We use cheap kittylitter in our indoor bun's pan. Keeps the oder way down and is easy toclean as they usually go in one corner. SInce they nevertouch it, it is safe. Others use wooden stove pellets.
No veggies or fruit should be fed until after 6 months old and thensparingly as treats. They can really upset thetummy and cause runny and loose stools. Since he is so young,he should be inside until about 3-4 months old.
If you have any other specific questions please feel free to ask. Hope he does well. Donna