After selecting US Dollar from the pop up window, the main window will change where you will need to then make more decisions.  In this window you will need to decide your deposit amount in USD value.

Enter a USD value into the Deposit Amount field.

Demonstration: > Funding > Deposit > US dollar > Enter a deposit amount

When you enter your deposit amount be sure to do so in a USD value.  Example: if you wish to deposit $500 then in the Deposit Amount field simply type the number plus decimal and the cents. No other character is required.

In this image the Deposit Amount in USD value is set to 785.00 BUT be sure to enter your own value of how much YOU want to deposit.

Demonstration: > Funding > Deposit > US dollar > 785.00