How to I care for my stray kitten?

Okay a cat outside my house had 4 kittens I plan to try and bring them all inside because I live on a main road and the last set of kittens one or two of them got killed in the road :( I am trying to keep that from happen and I want to give each kitten a nice home. I have one of the kitten inside now. She's sleeping in my lap. When I put her down she goes to a corner or under my bed and meows. I dunno if its because she sad and wants her family or if she has to go to the bathroom I had her in side all day and a few times before not for long. She was scared she a bit older now maybe 6-8 weeks old. Any ideas on getting her to use the liter tray or stop going place an meowing like that? :( or to get her to eat a little got her to drink water but she hasn't ate since I brought her in, or used the bathroom. :/