Working with HoMM5 files.

Please explain how to open a screenshot in Paint and make it readable.

You'll need any program that can read the tga format - IrfanView, XnView, ACDSee, Nero Photo Snap (usually comes with Nero), or even Photoshop. Use "Save As" to choose the jpeg (or bmp) format and save it. Then you can crop it with Paint if you want.