I was captured and upside down. I shot the pulley and fell, then it said to shoot rope arrows and to do that you press (m mouse) to shoot. How do I do that? I play on the PC version of Tomb Raider.
The action you're being asked to perform is "Alternative Fire" - with the bow selected as your active weapon, this will fire an arrow with rope attached to it, which will embed itself in specific parts of the environment (which can be highlighted with Survival Instincts) and allow you to interact with them.
By default, "Alternative Fire" is bound to Mouse 3 (middle mouse button, ie: pressing your mouse wheel). If you do not have a mouse wheel on your mouse, you will need to rebind this to a control that you can use.
I was also stuck on this xD but after rapid tapping buttons on the keyboard, every now and then it would finally shoot one. I finally narrowed it down, while aiming at where you want the rope to shoot to, press "n" then "space" and hold both for a sec it will then shoot a rope! I had to learn this way because I use my laptops trackpad