This article explains how to donate money using digital gift cards on Steam via a web browser or the Steam client.
How to Send a Gift Card on Steam
You need a Steam account to send someone a digital gift card. The person also needs to be on your friends list for three days before you can send the money. Here’s how to email a gift card through the Steam website:
Go to the Steam Gift Cards page and select “Send a Digital Steam Gift Card.”
Select an amount for the digital gift card.
