Nice game, coincidentally I too published a very similar game 4 days ago, maybe we can work together in future ;)
You have to push numbers and symbols to form an equation equating to the goal value. E.g. if your goal is 3, you can push the blocks 1,+ and 2 in either
| 1 |
| + |
| 2 |
or
| 1 | + | 2 |
format, which forms the equation 1+2, thus solving the puzzle and unlocking the next level.
I have put other stuff in more detail on the game page itself.