If you dont`t want to use specific code but only to turn on/of by pressing any button check this http://www.engineersgarage.com/electronic-circuits/relay-activation-using-tsop-1738. You only need scheme on the right side, the left side is IR tansmitter which you dont need. I think you shold place one Flip-Flop between transistor and TSOP which will save the currently state.