As an ageing newcomer to this game can anyone tell me how to grab the rope and swing after meeting the guide in front of the large door and going on the ledge to the left of this door. Thanks in advance.

Andy

http://tombraiders.net/stella/walks/TRAwalk/01caves.html

The on-screen instructions explain how to grapple-swing. Take a running jump off the ledge and quickly press and release Grapple (no need to hold the key down) to attach the hook to the metal ring above the doors and hang from the cable. If you don't press Grapple quickly enough, Lara will land on the ledge below. Turn around and jump back to the light-colored, tiered ledge, which is now ahead on the right. Climb back up and try again. If you're having trouble with this, try releasing the Jump key once you've made the running jump and Lara is in the air. Then quickly press Grapple.

If you need more help, please post back. And tell us what platform you play on, as some controls are different.