If you're talking about a commercially made screen top for an aquarium, you really don't need a tutorial. Just cut a piece of foil to fit over the screen, and tape it on. The tape should fit the outside of the lid, and not wrap around underneath it, where it would make the lid fit tight or not at all. I generally use saran wrap instead of foil, and clear package tape instead of duct tape.
You don't have to worry about leaving big gaping holes for ventilation. The lids generally fit loose enough to provide fresh air. I have a couple that the saran wrap covers the entire screen surface and a couple that I left a small area open for ventilation. They've been this way for almost a year with no issues.
Hope this helps,
Steve