Populate Dropdown Listbox using a Web Service

Hello, I would like to know how to populate a drop down listbox (dlName) from a web service with last and first name i.e. (LastName, FirstName). My Web Service XML that I am requesting is as follows:
<?xml version="1.0" encoding="utf-16"?>
<FindPartnerContactsAction xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
    <CompanyName>training</CompanyName>
    <IntegrationLoginId>cscw</IntegrationLoginId>
    <IntegrationPassword>cscw10</IntegrationPassword>
 
       <!-- Search conditions  Available fields are:
                - ContactRecID (number)
   &nbs ...