You can also use a public variable to store the path to the picture you want to display.
set the picture property in report designer to 'file', and use the variable name, say pix for example.
Then in your code:
public pix
pix = 'c:\yourapp\graphics\stdpic.jpg'
repo form yourform
Just change pix value to whatever the path is to the picture you want to display, before running the report.