Click on a square, then click on a number in the bottom row to place it. Your goal is to have each number appear in each row and column only once.
Take note of the inequality signs. For example, if you see ">", the larger number should be on the left of the inequality sign and the smaller number should be on the right.
You can click on a square twice to enter notes mode and write down a few possible numbers to limit the possibilities. Click the square again to leave notes mode.