In order to order hashrate you need to click Buy Hashrate in the left menu, choose hashrate and use the slider to set the amount.

Then click the Proceed button.

On the next screen, you will see the pre-invoice. If you are happy with your order, click on the checkbox below that reads "I confirm that I have read and agree to Terms and Conditions." and click the Proceed button.

You are now on the payment selection screen where you are to choose from USD payment methods.

Upon selecting the method you will be taken to a page with the information how to pay for your purchase.