Just got the game. I wonder if someone can explain to me how Tinkering works? Thanks.

Sure (although questions like this are better suited for the Rules forum).

The Runner spends a click to play Tinkering. The Runner selects a piece of installed ice. It doesn't have to be rezzed.

Until the Runner's turn ends, pretend that ice has the traits "barrier", "code gate", and "sentry" printed on the card.

Why is this good?

Well, you might notice that the Runner's icebreakers say things like "break barrier subroutine". This would not be useful against an ice that does not have the barrier trait. Thanks to Tinkering, the ice the Runner selected does have the barrier trait, and that icebreaker is now effective against that ice.

Long story short: Tinkering makes a run that occurs later in the same turn easier because one of the pieces of ice will be able to be broken by any icebreaker.

Thanks! I thought this might be so, but I wasn't sure. The wording on the card puzzled me somewhat.