SO, i have quickenings for one of my characters, but i dont have a clue how to use it, could someone enlighten me?

I know it has something to do qith r2, but what ?
Once you have a few charcters with them, you use them as combos - if no names come up on the bottom right keep pressing R2 to shuffle the box, until other characters' quickenings appear, that way you can have yourself a nice little combo and do some kick ass damage
You need to have a pretty much full MP bar aswell, youl know when its full enough because it goes yellow.
Then select Mist, then Quickening. Then use the method 'cobain_is_king' said.
It's more useful when you have more of them, two of my characters have 3 atm and the rest have 2, just be sure to stock up on ethers to restore mp. I only really use them on bosses, so I just go straight in with my first three characters, usually getting around 11 hits in a combo, doing about half damage, then I use my three weakest characters to do the same, leaving the boss with only a little it of health left, then I bring Vaan back out, use an elixir and have him use his third quickening again, easy.
aha cheers guys, so really it depends on more than one of my characters having them ?

Also, is there any button combinations i need to press when the countdown thing is going down ?
Just press r2 during the time to make others appear but you need to have peeps with Quickenings before you can do over two if your lucky your guy will get a chance to redo his if you pressed r2 a bunch of times, but don't gun it do it like have some patience becuase if you go nuts you might miss your chance.
The more is better. Nah no combinations, it'll come up for exaple 'X: Vaan:White Whorl' or 'O: Fran: Whip Kick' so you would press X to use Vaan's, but if none were there, you would press R2 until one appeared. if it says 'X: Vaan:Mist Charge' you press x to charge his mist, then the next time it will say 'X: Vaan: Red Spiral' etc. I know it seems a little complicated, but you'll pick it ip
post above me pretty much says it all.... but for some insane combos, make sure you START WITH A LEVEL 1 QUICKENING. That way, if someone has a level two or level three coming up, you can get some time back (you get extra time for going to the next level of quickenings). Also, if you have the option for a mist charge or an attack, ALWAYS mist charge. That will not only charge up the mist charger's mist bars, but also the person who was going to attack's mist bars (most of the time). When combo is over, switch out one character and get another mist ready character in, rinse and repeat.