Hi greybird,
I wish I had time to make some tutorials and fine documentation for this plugin. The point is, I’m only a hobbist developer, I deal with something completely diferent everyday, and really have no time to do it.
Also this plugin started as a very small project (you can download and install the first version and see how it was simple). It grown up a bit, and by the time it was more important for me to add new features than to make a documentation since none ever asked for this. I tried to make everything self-explaining and I think it really is.
About the offset: it’s also self-exmplaining, but one can always ask.
It ‘moves’ the watermark e.g. when you set the watermark position to top-right corner, then set the ‘x’ offset to 100, the watermark will appear the 100px below the top edge of the image (and 0px from right).
(notice: if you set your watermark positon to the center of image, the offset still works, so your watermark would be applied ‘100px below the center’ so the central point of the watermark will be 100px below the central point of the picture. Please set offset to ‘0’ if you want to have the watermark really centered).
If you have any other questions/don’t know how to achieve some desired behavior of the plugin, please ask and I’ll respond as soon as possible.