Making the stamp is very simple.
First you draw the something you want to have on the rubber with a pencil on a paper.
Then put the drawn part on the rubber and use the back part of the pencil to rub on the paper.
In this way you will copy the drawn something on the rubber.
Now it is time for carving. Please be careful while you are using the knife.
When you are done test your own rubber stamp on a paper and maybe make an ATC Card with it :)