Using the "start" command generally works like this:
start "program" "file to load with program"
Say, for example, you wanted to start "Firefox.exe" (a web browser) and wanted to go to the web page "
www.computerhope.com"
Your batch file would look something like this:
@echo off
start "C:\Program Files\Mozilla Firefox\firefox.exe" "
www.computerhope.com"
Notice that the executable and the address are in separate quotes. Also, keep in mind that I used a web page in this example, but you could replace the web page with a text file, or any other file that you could open, and you could replace the executable with anything.
Another example, suppose you wanted to play a certain song in Winamp:
@echo off
start "C:\Program Files\Winamp\winamp.exe" "C:\Daft Punk - Technologic.mp3"
Hope that answers your question ^^