You can put this solution on YOUR website! Draw a straight line with tick marks, like a very thin ruler, and put zero in the middle. Then put "1" to the right of zero, write "2" to the right of 1, etc until you've gone to a decent number. Then go back to zero and place a "-1" to the left of zero, -2 to the left of -1, etc. and thats it. Thats all thats to a number line.
Here's a visual to help out: