I really dont wanna sound mean but what do you mean you cant figure it out? did you play any of the melee jobs in this game or is your first one? again not saying it to be mean. it literally tells you how to play it.

they named it hind and flank
they colored it red and green
its only 2 buttons.
it gives you a buff 3 steps in advance that litrally looks like the ability your next combo is going to end with
its basicly a more simple version of samurai.
1 combo gives the speed buff
the other gives the damage buff.

find a target dummy. go slow, read the tooltips. just go as slow as you want. then when you get the hang of it speed it up. you'll get it in your muscle memory in no time.