This tutorial assumes you've already logged in to your WHMCS admin panel
Now let's learn how to place a new order for a client
1) Click Place New Order

2) Select a Client from the list and the Payment Gateway with which they should pay

3) Choose the Product/Service this client will order

4) Enter the domain name

5) Click Submit Order

An invoice for the order will be displayed

That's it! You now know how to place a new order for a client in WHMCS