You can put this solution on YOUR website! What don't you get? Roman numerals??
I = 1
II = 2
III = 3
IV = 4 -- when you place a smaller number (like I) before a larger number (like V), you subtract 1 from 5 and get 4.
V = 5
VI = 6 -- when you place a smaller number (like I) AFTER a larger number (like V), then you ADD 1 to 5 and get 6.
X = 10
L = 50
C = 100
D = 500
M = 1000