Hi Madhi,
You can:
a) Use the methods and properties of the TestedApps/TestedApp object to set the proper value of the TestedApp.Path property from the script (see relevant help topics for more details); or
b) Create a Project Variable that will hold the path to the tested application and assign the value of this variable to the TestedApp.Path property from the script like in case a).
Also you may consider running your test project in the Network mode ("Sharing Projects and Project Suites Among Several Testers" help topic) in which case the path to the tested application may be different when the test project is executed from different computers.