Pics Of The Sizes Of A Vigina,, What Is The Best Way To Re-size My Digital Pics To The Standard Sizes?

What is the best way to re-size my digital pics to the standard sizes? - pics of the sizes of a vigina,,

I prepare my photos for sale online, and you want in the formats of various sizes. I use a 7.1-megapixel camera. I need the size of my files in popular formats.

Some software is that for me for the PC? Or is there another way to simplify this for me?