The easiest way is probably to make an account with Coinbase, which allows you to purchase cryptocurrencies on their market and transfer them directly into 4chan's account. This is very fast because it only moves numbers in Coinbase's balance sheets without making any transaction on a blockchain at all (which can take a while, especially with the original Bitcoin network that only validates a block of transactions once every 10 minutes on average). The proxy service passget.site, which has been mentioned several times on /vip/ over the last months, operates on such a (commercial) Coinbase account.
The downside is that Coinbase only lets you purchase crypto in selected countries (North America, most of EU, Singapore, Australia) and has stringent requirements on ID validation (usually all three of phone number, photo ID and proof of address). Sadly this is required because crypto is often used by criminals (and entities such as 4chan) which cannot use traditional financial services, and Coinbase is by far the largest player in that area.
There are several other exchanges in other countries with different grades of validation (maybe even one operated by your bank), your mileage may vary there. With those, it may be required to set up a "wallet" of your own which holds the cryptographic keys to accounts that you can transfer your funds in and out, in case they don't allow you to directly cash out into Coinbase's invoice address. Don't be fooled by complex guides on how to set up a wallet securely in case you want to hold on to crypto as an investment; simple wallets such as Electrum (for Bitcoin) or Electron Cash (for Bitcoin Cash) are fine for just moving small amounts.
I agree even this short explanation is already complicated if you never have dealt with cryptoshit, and it's easy to get defrauded because this alternative system places all the trust and diligence of banks on you.