Hi ayourix,
An easy way to do it, is from Push2Run's Main Window, just click on File - Add and then in the new blank card that opens up, simply drag the program or file icon for whatever you want to open up into the 'Open' field on the card.
If you still have questions, please be sure to read through the help here:
https://www.push2run.com/help/help_v4.2.0.0.html#change
and then if that didn't help, please post back with more exactly where you are getting stuck.
Of course, if this helped, please let me know too.