mmiotte, my DD is now 6 months. I remember the first day home from the hospital as if it were yesterday! I felt totally lost at first, but found the way to cope is to take one step at a time. Get DH, or whoever else is there with you, to make a cup of tea, introduce baby to her new home, and take half an hour to just sit and let it sink in a bit.
If you are BFing, just concentrate on that for the first few weeks. Definitely demand feed, however you are feeding, and sleep whenever you can. Don't worry about housework - if you can get a relative/friend/neighbour to do a bit of hoovering or washing up or whatever, then do!
don't worry about dressing, but you must eat, and will probably feel better for a nice shower too. don't worry if baby is crying - as long as she is fed, with a clean nappy and in a safe place, ie the cot, then you can take 10 minutes to wash. Supermarket delivery services are a life-saver, and a full freezer of ready meals, home-made or bought, is essential !!
however well meaning, visitors will generally focus on the baby and forget that you just gave birth, so be a bit selfish and ask them to stick the kettle on themselves, nip out to the shop to buy milk/choccy biscuits etc! Also, if you don't want any visitors, be firm and just say no. They can come round later when you are up to it.
Don't worry about feeling you know nothing - even if you know everything you still know nothing, IYSWIM!!