Using masks on photo

I have a few photos whose contrast/colours I'd like to change and I'm tying myself in knots with the use of masks. When trying my first mask of one area, I found it a bit disconcerting to find that the pink overlay disappeared as soon as I'd applied the first effect. After playing around a little, I found that the masked area could still be modified even although it wasn't that evident I was using a mask (layer menu aside)

I also can't seem to find an easy way of then modifying only the rest of the photo outside the masked area. In order to invert the mask, do I need to copy the shape used for the original mask, and then invert?

What if there are several areas in the photo I want to mask and amend differently, as well as the entire background itself?

I've tried searching the forum for a tutorial but without any luck. Could someone please post a simple example of any photo, showing how to mask off more than one area and treating them and the background as separately enhanceable areas?

Thanks

PS Using XPGD6 on Windows 7

I simply clone the photo and use the shape editor tool to mask and then slice out the parts of the clone here is an example.

PB In my opinion, the Mask Tool is totally confusing. But there is a better way to do what you are asking.

There is a new transparency mode called Enhance. Create a mask shape such as Frances has indicated, then apply an Enhance transparency. You will not see any difference and the mask will become totally transparent. But now you can edit the shape with the Photo Tool.

If you need more detail, see this tutorial.

The enhance transparency is however limited to just Brightness, contrast, saturation, and temperature sliders. If you clone and slice the photo you can use much more, such as sharpen/blur, and the new levels/brightness feature.

Many thanks to both of you - I'll have a go with both methods and see how it goes. Cheers