Click on Buy on the home screen. You can buy crypto using My wallet if you previously added funds to your account. If you're not sure how to do that, we have a few article here that can help you get started.
In the Buy menu select My Wallet, input the amount you want to Spend, select the Coin you want to Buy, and then click on Buy Now.
You will get a confirmation screen, explaining how much you pay, how much you receive and the service fee. When you're ready click on Confirm.
Congrats! You just bought your first crypto!