If you want to buy cryptocurrency - create an Order to buy cryptocurrency.
You can do it in the "Exchange" section.
Select a trading pair, then, under the trading table create an order to buy crypto currency:
- select "Buy"
- specify the amount of cryptocurrency;
- specify the price;
- click the "Place buy order".
Detailed instructions on how to create an order can be found here.
The order will be executed automatically, immediately after the buyer and seller's orders coincide.