First off, you'll need a wallet and some algos. Check out the homepage for guides on how to get started.
Go to AB2 Gallery and toggle the menu in the top right corner and click "Connect Wallet".
Go through the steps in MyAlgo to connect your wallet.
If you have multiple wallets in MyAlgo, choose which address to connect to.
Now that your wallet is connected, go to the collection's AB2 Gallery page.
You can find any collection by searching for the collection's Algorand address using the search bar on AB2 Gallery.
Another way find a collection if you know the address is by going directly to the page. If the wallet address is
KVC4EZQTW7M3RQWJZZXVDJ7W6THDKK7SEOKAYYSXVBN3U6HD3KKNZ2QL4E then the AB2 Gallery url for that collection is https://ab2.gallery/address/KVC4EZQTW7M3RQWJZZXVDJ7W6THDKK7SEOKAYYSXVBN3U6HD3KKNZ2QL4E.
If the collection has any open listings, click on one you like and scroll to the bottom of the page.
You'll see a green button with a price. You can click on the green button to purchase the NFT.
A modal will appear after clicking the green button. Confirm the purchase to buy your new NFT!
If the transaction is successful you will see the NFT in your wallet pretty quickly!
To view your NFTs on Ab2 Gallery, you can go to your profile and click on the "Collections" tab.