I want to create my images into 1" size, what program do I need?

[mysweetskull.com]

It's a hobby thing. I want my images to fit into a 1" x 1" square size onto a sheet. What program can I use to do this?

 

[N-D]

I know that one inch has 72pixels.
Example:
1" x 1" = 72px x 72px
2" x 2" = 144px x 144px