Download Coinbase on ios or android
Scan you passport to them using the app
Enter your credit card details or bank details.
They are an American exchange.
Initially they restricyt yopur puchases to an amount each week on a credit card.
i bought at £325 a week initially but can now buy £500.

Once you have bought the Cryptocurrency move it away from coinbase to your own private wallet.

Make certain you know how the wallet works,

Don't invest more than you can afford to lose.

Find someone who knows what they are doing and get them to help you.

DO NOT LET THEM SEE YOUR PRIVATE KEY!