I picked up a stray kitten 4 years ago. I think I should be able to help you.
First of all, you need to send the kitten to the vet for a thorough check-up. You can request the vet to clean its eyes, nose and most importantly, ears. If the nails are long, have them clipped as well. The vet will then give the kitten a tablet for deworming purposes, and it will be given a vaccination jab. I can't remember how much the visit cost but I think it is around 100.
To train the kitten, you have to start when it is young. You would need a litter tray, litter (clumping sand), some liners, and a scoop.
Some advise given by friends is, try not to feed the kitten fish. Give them dry food like Whiskas, stay away from Friskies, they cause liver or kidney stones. Always provide a dish of tap water. NEVER give them milk. Their stomachs won't be able to take it, and they will vomit. Many pple think cats like milk, they do drink, but it is not good for them.
Once you have fed the kitten, bring it to the litter tray, let it smell the sand, and it will pee and poo in there. Cats are generally clean animals, they will cover their waste with sand.
Get the clumping sand, it is not messy. Try Snappy Wood Clumping Sand, it is 8kg, and costs around $13. Cats like their litter tray to be clean, so try to make it a point to clear their waste with the scoop as often as you deem fit.
When the kitten is bigger, get them a scratching post. This will be most helpful as you wouldn't want this cutie to damage your furniture.
Generally, they do not need alot of attention, but to build a beautiful relationship, spend as much time as you can with it, and play with it. Cats find it amusing to run after a crushed ball of paper. Oh! If you buy the 1.5kg Whiskas dry food now, it comes with a toy. My cat likes it very much! It's a tiny rod and at the end tied to a stuffed fish with red furry fins!
Hope the above helps. If you need more info, lemme know. I try my best to help.