In the Free Mode you will be able to form as many words as you want using the letters that are given to you in each level.
You will be able to spell your words in the game area, in which you will see the given letters for the level you are in. Once you spell the word, the game will indicate if it's valid or not and, if it is, it will be added to the information area.
There you will see every correctly spelled word so far and the number of points you need to complete the level.
You will have the chance to change the order in which the letters are arranged by tapping on the button that appears on the bottom left corner of the screen.
You will also be able to arrange the words you've found on the information area alphabetically, by tapping on the button that appears on the lower right corner of the screen.