fixed6373

A visa has not been approved for your brother.  USCIS has approved the I-130 petition.  An approved I-130 does not mean that a visa has been approved.  It will probably be another 5-6 years before your brother becomes eligible to apply for an immigration visa.  
 
According to Table B of the May 2021 VIsa Bulletin, beneficiaries with a Priority Date before January 8, 2013 are eligible for further processing.  Your brother's PD is March 16, 2018, so his case is not eligible for further processing.  Nothing needs to be done and nothing can be done until your brother's PD becomes current in Table B of the monthly Visa Bulletin.  Only then will the CEAC website allow for payments of the DS-260 and I-864 fees.

For now, you wait until your brother's PD becomes current in Table B of the monthly Visa Bulletin.  

As the saying goes, take it from the voice of experience. We filled out the I-129F with whatever was handy, a black or blue pen. Turns out signatures were mixed colors some black some blue.
Upshot was when I sent in the package to USCIS the whole thing came back to me a week later and told me signatures were photocopy not originals (the ones in black) and I had to write a letter saying NO they were originals in black ink. So that cost us about another 12 days in processing and an RFE.
They did accept it when I sent it back with cover letter saying they WERE original black signatures. But it was a 12 day delay in processing our I-129F.
So I learned, use blue ink at least for all signatures, fill out the rest in black is fine, but use BLUE INK for all signatures is my experience.
And for what it's worth we did make it through the interview and approval, and the signatures in black ink on the orginial petition were never questioned again.