Hi Karen,
I don't have windows 7 or 8, as I prefer XP

I save all photographs and documents on the computer's wallpaper screen. Then I right click on photo or document and a drop down box appears with the programme paint.
Alternatively, click on start button at bottom left of screen; start/all programmes/accessories/paint.
If you use Adobe photoshop 6.0; and whilst the photograph or document is open in that programme, click on image/adjust/invert.
I hope this helps you find paint, or to invert

Kind regards
George4