Hi guys, I finally got my NVC Welcome Letter (ACL). Anyone have a breakdown of how this stage works?

First and foremost is the 601a, right? Then the DS-260?

The letter says I need to take the following actions:
Step 1: Choose an agent (please allow up to three (3) weeks for processing before continuing to Step 2)
Step 2: Pay fees online at ceac.state.gov (allow up to one (1) week for processing before continuing to Step 3)
Step 3: Submit visa application form online at ceac.state.gov
Step 4: Collect financial documents
Step 5: Collect supporting documents
Step 6: Submit financial and supporting documents in one package to NVC

What actually comes first?