You need to place all your tiles on the board in one turn. You could wait for it to happen naturally, but that might take some time. Here's how you can get it in a couple of minutes:
Start a game of yourself
against another local player using the same controller.
If the other player plays first, just skip a turn.
Then build one word vertically.... any word that uses a one point letter, R, S, T, E, O etc.
The other player just skips a turn.
Now think of an easy 8 letter word that you can build using one of the tiles already on the board. The easy words of course depend on the letters you have, but here's a few suggestions (using
http://wordfinder.yourdictionary.com/letter-words/8):
assistor
retorter
assessor
retiarii
assesses
retirees
retirers
atresias
treatise
resister
resistor
resorter
retastes
assertor
tristate
retreats
retrorse
assister
There are thousand of words to build.... but these are easy because you will not have to wait long before you get the letters you need.
Once you've decided which word you're going for, keep exchanging letters you don't need and keep skipping a turn with the other player. Once you've got all the letters, just build the word.