Once you get the hang of it, it's pretty easy.
Lets look at decimal:
0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10
Notice how, when you got to 9, you couldnt count any higher in the 'ones' spot, so you carried it over to the 'tens' spot?
The same goes for binary. Except with binary, you dont count up to 9 and then rollover, you count to 1.
0, 1, 10
Notice that when the lowest bit position couldnt get any higher than 1, so it rolled over into the next highest position.
To continue:
0,1,10,11,100,101,110,111
It when every bit position gets filled with a 1, the next increment rolls over into the next highest bit position.
When we count in decimal, we can put zeros in front of the number, because they dont count for anything. FOr example:
0000, 0001, 0002, 0003, 0004, 0005, 0006, 0007, 0008, 0009, 0010.
The same goes for binary:
0000, 0001, 0010, 0011, 0100, 0101....
Hopefully that helps to get you started. Try looking on
www.howstuffworks.com
I think they have an article on binary.