A rabbit's main diet should be good quality pellets, fresh hay (alfalfa, timothy or oat) and fresh vegetables. Anything beyond that should be given in limited quantities. Pellets must be high in fiber. Fresh foods also provide moisture in diet, which is good for kidney and bladder. When feeding with vegetables, dark leafed greens are suggested.
Fruits can be given in small portions. Because some fruits contains lots of sugar and may cause your rabbit gain lots of unwanted weight when given too much.
You can also feed your rabbit with rabbit feed sold in supermarkets, petshops and veterinaries. They contain essential ingredients such as corn, wheat, peanut, sunflower seed, bean, pea, locust, barley etc.
Avoid feeding your rabbit with the same food all the time, try to feed him/her with a wide variety of foods in small amounts.
Always make sure your rabbit has fresh water all the time.
Also avoid feeding your rabbit with plants, vegetables that you don't know, because they may be toxic. For a detailed toxic plant list, please visit: http://adoptarabbit.org/articles/toxic.html