You just need the I-130 to start and then file the I-864W when it gets to the NVC. You will also need written permission from the father for the process.
You need to file form I-130 with USCIS first. You do not do anything with the I-485, that’s if your child is inside the US. Once the I-130 is approved (could be anywhere from 8-12 months) USCIS will then forward the petition to the NVC where you need to provide additional documents including the Affidavit of support. You can use form I-864EZ if you are the petitioner, your income alone qualifies and the child is the only beneficiary. Or you can do the I-864, it just ask for more information. The I-864 is like the base, when in doubt, use the I-864. The other ones apply to different specific circumstances.
Once all the supporting docs are received by the NVC, they will forward it to the nearest Embassy/Consulate where the child reside. He/she need to go to the Consulate to attend an interview and get the immigrant visa. The child can use the immigrant visa to enter the US. I also believe the child will automatically be granted US citizenship because he/she will be less than 18 when enter, and will be in your custody, a US citizen.
