I have seen a tutorial on how to place a small coloured sqaure on the windscreen to aid with lining up on the runway during landing, but can anyone tell me how to create say an arrow in Photoshop and use this as the landing bug which can be toggled on and off?

You don't need to make your own.In FS select ViewsView Options then select the marker you want from the drop-down list under Axis Indicator.

Thanks for replying. I tried this but unfortunately my cockpit (Cessna 421c Golden Eagle) covers up the axis indicator, and as I like to land with the dash showing, I was wondering if the A.I. could be moved up