I got a PPD test the other day and now I have a reddened area about 1.5 CM in diameter. It looks slightly raised but not firm to the touch. Tb?

See details. The PPD is not as accurate as you may think. Ask the doctor to order a quantiferon gold blood test for tb. This is more definitive.
48-72 hours. To be read after 2-3 days measured from indurated-hard end, to the other hard end. You may be ok is just red and not hard. The doctor reading it will let you know.
Positive. Your PPD test is positive. It means that your body has been exposed to TB bacilli in the past. It does not necessarily mean that you have an active infection. You will need a chest x-ray to determine this. You would also need an evaluation by a physician.
TB test. Your TB skin test sounds like it might be positive. That does not mean you have active TB but suggests that you have been exposed to the bacteria. You need to have a professional read that test to be sure it is positive. They would then suggest a follow up test to confirm and maybe a chest x ray if needed.