If you're using the website I linked you:
1. Select the grid size.
2. Enter the initial configuration. 0 = Off, 1 = On.
3. Click 'Solve'. The solution will appear on the left.
4. Click each space with a 1 in the solution.
There's a general strategy called "Chasing the Lights"
1. Starting in the 2nd row, click each space with a light above it.
2. When you've done the bottom row, there should only be lights on the bottom.
3. Look up a table that will tell you which spaces to click on the top row, based on which lights are on.
4. Chase the Lights again. This time, when you finish, all Lights should be off.
