Newbie Raid question

[mosaicex]

There are plenty of ways to do this.
If you are DRK or WAR, simply use your gapcloser to go back to the boss and wait until the ice floor disappears and adjust your position a little as to not clip with anyone else (usually melee dps)
If you are PLD you can either slide back to center and wait there (adjusting your position slightly after ice floor disappeared, like previous case) or simply slide back to your previous NE position (using back on controller, but I'm not sure).