Now that we have our data bank we need to be able to reference it in a script. Typically login will be done at the application level and therefore handled by a login form. Internal intranet applications may use some kind of Single Sign On (SSO), AgileLoad can handle this. Please search the help section for the SetAuthentication() function. This supports Basic Authentication, Negotiate Authentication, Kerberos & NTLM (NT LAN Manager).
To change a variable with the AgileLoad GUI use the story board to navigate to the request where the login credentials are sent, alternatively if you know where that is in the script place the cursor on the request (SUBMIT) and click the Record Request Details button on the toolbar. You will see a yellow arrow appear in the left hand margin of the script.
Using the HTTP Data section (to the right) click on the Client tab (in the middle of this section) to see the request data, to change this click on the parameter you wish to change (‘login’ here) and use the control at the bottom of the screen to switch from Value to Variable. Choose the variable name and click Apple Changes. You will see that the new value in the grid has changed to the variable name and that the script has been changed to reference the variable itself.

Now you are ready to test your script, the best way to do this is to execute it and analyse the replay differences. Use the client tab in the replay differences screen to check that a different user name has been sent and that the response from that request is as expected.