Here are settings to create one user comes up at a time and sends a GET Request. When the first user is finished the second user then comes up and sends the second GET Request in the action list. To do this use forms database and assign variable. Please see settings/pictures below for reference.
1) Configure the load for 1 user.
2) Then configure the Forms Database (in Client > Action > Forms tab) and enter your strings (for the example IP addresses are used). In the action use ASSIGN VARIABLE to call the forms database. In the for database is called 'my_host'. The .$ after the name invokes first column in the database. For more information on forms database and assign variable please refer to Avalanche online Help (Help from the Avalanche GUI).