There are two methods:
1. To open the application  before testing it.
2. Or to give the path when you are running the test

Click on Insert.
Click on Step Generator.
Step Generator dialog box opens.
Select "Invoke Application" from Operation combo list.
Click on row below "Value" in the Arguments section.
Enter the .exe path for the application in the value 
column. For this go to your application properites, and 
copy the path.
Leave all the selection as it is, and then click OK.

You will see in the expert view of the QTP test pane

InvokeApplication "C:\....."

You can use Step Generator by using Short key F7.
then step generator window will appear, and do the settings 
what u want

Just press F7 key
and select involkeapplicaion "pah"
or
systemuti.run "path"

Click on Insert.
go to Step Generator.
Step Generator dialog box opens.
Select "Invoke Application" from Operation combo list.
Click on row below "Value" in the Arguments section.
Enter the .exe path for the application in the value 
column. For this go to your application properites, and 
copy the path.
(Or)
Just press F7 key
and select involkeapplicaion "pah"
or
systemuti.run "path