To use this application you have to install the app on your device and run it. Then you can use the textarea on the top to fill in your current sudoku. If you have a gap you place a zero (0). Otherwise you place the number. After 9 numbers/gaps you make a new line. In the following you will see an example:
003050079
200600150
089021000
100078906
908200005
020040800
805062090
090507601
700400080
At the current state, there are some issues, that it not solves every gap. But then it is very easy to solve it by yourself.