Where did you get him that you don't know what age he is? To me he looks about 6 weeks old, which is extremely young. He shouldn't leave his mother until 8 weeks.
*You could bath him carefully in warm water in the sink, shampoo him gently but not doing his head. Then dry him gently with a towel, making sure he doesn't get cold. Be sure to make it a positive experience for him, be gentle and kind.
*He won't be wormed, so don't let him lick you.
*Be prepared for a pretty sleepness night for the first few nights as he is away from his mother and familiar surroundings and will likely howl or cry through the night. Be patient with him, don't just dump him on his own in a room, comfort him.
*For food, depends if he is weaned or not. Try a bit of mushed up canned puppy meat (just a bit as new food will upset his tummy.) Bread in milk is okay, but again not too much. (some say this is good, others say it is not)
Make sure water is available for him too. Depending on his age he will have to be fed often. For very young pups it is every 2-3 hours (it has been a while for me so if someone knows different speak up). You can also buy puppy formula at pet stores if he needs to be bottle fed.
For feeding do some research, http://www.peteducation.com/article.cfm?c=2+1651&aid=704.
*Rule of thumb....'in one end, out the other'. Straight after eating he will need to go poo and pee. Start house training him straight away by taking him outside on a lead and see if he goes to the toilet straight after he eats (carry him outside, he won't know how to walk on a lead and is too young). Praise him when he does go toilet and he will get the idea. Don't tell him off if he goes to the toilet in the house, he can't hold it in as he is a baby and he is too young for real training.
*Looking after a puppy is a lot of hard work and not that different from looking after a human baby. He needs to be fed, cleaned up after and watched constantly. He is definitely too young to be left alone.
*When we have a puppy we usually set up an area in the kitchen, blocking it in with child gate or whatever we have. Then lay newspaper on the floor for piddles, water for the little guy and a nice comfy bed in a dog crate that gives the puppy somewhere safe to retreat to.
Just adding stuff as I think of it. It has been a while since I have had a puppy, the last one is now 2 years old. But he was 6 weeks old when we got him and had to be bottle fed for a while.