call button click externaly(automatic)

Hi, I want to stress test my asp.net application. Im using a MS WCAT 6.3 tool. I made a virtual client which is sending requests to my localhost(http://localhost/test/Default.aspx). There is a simple web form made of two textboxes and one submit button. On button_click the values from textboxes are written to my MS SQL database. I need to set the values of these objects from external script. And specially click this button to call the function which writes to database. The WCAT tool can send data to my webserver with POST and I can set the url like http://localhost/test/Default.aspx?TextBox1=value&TextBox2=value , but how can i achieve to click the button and write to database? This is the wcat script:
transaction

{

id = "Default Web Site Homepage";

weight = 1;

request
{

verb=POST;
url = "http://localhost/testova/Default.aspx?TextBox1=value&TextBox2=value";

}
.... ...