My track-gimping page is also at:
http://templot.com/companion/index.html ... _track.htmThe GIMP pages are actually the most viewed on the Templot web site. They have remained unchanged for 10 years and are due for an update.
You might find The GIMP a strange program to use. It scatters itself across the screen in several separate windows which have an annoying habit of hiding themselves behind each other while you are working. I find that I am constantly having to click them back from the task bar.
If you are looking at the image window, first click the
Dialogues > Tool Options menu item. On that dialog window click the
Perspective tool icon:

Now click on the image. The grid should appear, and also the
Perspective dialog window containing the
Transform button. (There is a lot of additional functionality available by right-clicking on the image.)
regards,
Martin.