I've purchased on Aquabid; it's very simple. I believe there's a sticky on this site, plus there are instructions on the Aquabid main page.
All you need is 1. MONEY, 2. a PayPal account; 3. email and 4. a mailing address.
What you do is buy the fish (PayPal is really you're only practical choice), then choose the "transshipper" closest to you. The overseas seller will ask you which transshipper to send the fish to. Answer that email w/ your choice. I always cc that transshipper. The selected transshipper will ask you to pay them for shipping to you (again, PayPal). Make sure you use UPS Express shipping. (I have them mark "hold for pick up", but my local P.O. seems to think "Hold" means "put on the freezing truck all day then cram the fish in a mailbox".)
This simpler than it sounds, really!! These people are pros & if they need more info from you, you'll hear from them.
Express shipping is expensive, but shipping can be on as many as 6 fish at a time, so 35 divided by 6= $5.8333 per fish. Of course you've probably paid $20 for the fish, so it's pricey, but WORTH IT! Petco/petsmart/LFS is hit-or-miss. People (myself included) have purchased wonderful fish there, BUT if you want a certain color/fin type, they'll probably have it on Aquabid.
4 bettas: Butch, 3-year-old violet male PK EE & 3 girls in a 30 gal sorority. I do not name the girls anymore! 1/2 of them die within a month.
30 gal: 9 Oto cats, 4 Ocellifer cats. Inverts: Cherry shrimp & 2 assasin snails.
10 gal.: Butch, his 5 oto cats, 3 assasin snails, and a few snails the assassins haven't caught.