I can explain how to use it quite easily.
Just give me a moment to download the program again. I deleted it after my last clean.
Also... got, try ZipGenius. It's free and works really well. I've been using it for five years now.
EDIT:
Step 1. Extract the files. Don't worry. If you're downloading it from the SonicRetro site, it will have no viruses. .7z is also the format that they used before .zip came along. It's old.
Step 2. Open rotSprite.
Step 3. Choose the image you want to resize and/or rotate.
Step 4. Choose the output source and the name of what the file will be called. It will automatically be saved as a .bmp however, .bmp are high quality images and can be saved again in Paint without ruining the quality.
-- Resizing --
Step 1. In the (Rotation Angle) category, replace the numeral with
0.
Step 2. The scaling factor is the degree you wish to change. A scale of 2 is double the size of the original image. Be careful with this as you might have to play around a few times to get it to work. Numerals such as 1.05 and 1.32 and even 1.045326 are applicable scaling factor numerals.
Step 3. Choose how many frames you want to export. The default numeral is 1.
Note: You must isolate all frames before resizing. An entire sprite sheet can cause many problems if you try to resize it all at once.
Step 4. Choose Run.
Have fun! Remember that rotSprite won't produce perfect results. However, the program is better than normal resizing/aliasing software. You'll still need to clean it up but not as much.
-- Rotating --
Step 1. Replace the rotation angle with the angle of your choice.
Step 2. If you want to resize at the same time, jump to Step 2. of the Resizing Guide.
And that's all there is to it.