I didn't actually use a scanner, but I should get to that.
To every barcode is a start and stop character. These usually have a large space after them, like this one does.
But to decode it manually, you need to find the numbers. Notice the bar I encircled in red. This is 1 bar. Now, how many bars can fit into the first block of the barcode? Most likely 2. So that would be 11. How many spaces in between that and the next bar? I guessed. It will be easy with a grid, but I don't want to make a grid when not sure of what's a 1 and what isn't. Say, 6 spaces. 110000001. Since the Single bar is after those 6 spaces, you add a 1. But it's not binary. A complete list of the numbers can be found on wikipedia.
If this post wasn't to helpful, it's because it's early and I haven't had much time writing it. I will be back to elaborate.