For beginners only...

1. Open Paint.net (pdn).

2. Once your layer has been opened, click on image option in the tool bar section at the top

3. Choose the Resize option, you should see these numbers listed below.

maintain aspect ration box checked

w: 800

h: 600

resolution 96.00

Print size:

w: 8.33

h: 6.25

4. To make the layer say an even size like 12 x 12 , first uncheck the aspect ration box. The go to the print size w: 12 and h: 12.

Everything should automatically change to

w: 1152

h: 1152

resolution 96

print size

w: 12

h: 12

I am posting this here instead of the message board for this particular software because I found it almost impossible to find simplied answer to this. I hope this helps others that are trying this program. This is my starting point so far.