SharePoint - How to Supply XML parameters in a SOAP Service Connection with SharePoint Designer 2010

Hello,

I already created one web service in asp.net.
Now i am trying to use this web service in SharePoint Designer 2010.

In this web service i want to use display list data method. For this i have to pass values in three parameters and after that it will display data list.
In my method i passed one parameter which is change every-time because it depends on username of SharePoint current UserName.
So how to add any parameter value after add data source in .aspx page?

I attached one image of my problem.


Thanks.