I added a guide to this post:
https://steempeak.com/sdcd/@cadawg/sdcd-steem-dollar-conversion-day-1-spud-compatible#how-to-buy-sbd-and-then-use-the-convert-function

It boils down to:

1. Send STEEM to @bank.sbd with the memo swap (No Fee)
2. Go to SteemPeak (login) -> Your Wallet and wait for the SBD to arrive
3. In SBD, next to the send button, there is a dropdown, click convert to STEEM
4. Enter The Number of SBD to convert in the field
5. Enter and confirm with SteemConnect or Keychain
6. Wait 3 Days
7. Repeat if you're feeling nice!

(I'm online on discord if you need help)

@cadawg