The number of 'gangs' is the number of plastic flick switchovers on the front plate, the number of 'ways' is the number of contacts on each switch. You are saying you have a two gang, two way switch from your description in the question (though I suspect you may actually have bought a one gang two way switch).
Ignore the second (gang) switch completely, and contact the light up using the COM and one of the Ls (either L1 or L2 - it doesn't matter which).