It’s a simple system to learn. You can use this betting system for just about any game, so long as you can make even-money bets. The 1-3-2-6 system is relatively straight-forward. Here it is how it works :

Place an even-money bet. For example, place a bet on black/red or even/odd in roulette. For the following steps, we’re going to say we made a $5 bet.
If your first bet wins, you’ll now have $10. The next step is to make another unit-sized bet – in this example, $5 – to the money that’s already on the table. So, we’ll have $15 total on the table.
Say this bet wins, too – you’ll now have $30. The next step is a 2, which means we want to leave 2 units on the table, or in this case $10. So, remove $20 from your bet (leaving $10).
We’re going to say this bet also wins. You’ll now have $20 on the table. But for the last step we want 6 units on the table. So, we need to add another $10 to make our total $30 ($5 x 6 units).

If you win this bet, you’ll have $60 on the table. You’ll want to remove this amount, and then on your next round you’ll start the cycle all over with the first step.

But the bottom line is that betting systems don’t work because they do nothing to change how the game is played. You’re not altering the rules or payouts, so you’re not changing the house edge.

For that reason, you’re still playing at a disadvantage.