Creating A Light Block

In the second page of the block making, (where you put the name, drop, creative tab...) the square from the left, down part has an option called "Luminance". In there you go to help (?) and search the block that you want to compare with. If you want the block emmit as light as a torch, you search torch and copy the number near to it (In the light level) . Then in the luminance you write that number. Hope you understand and it is helpful.