You need a multimeter that measures resistance. The resistance of the secondary winding will be low, maybe 1Ω to 5Ω.
The resistance of the primary winding will be much higher, maybe 200Ω to 500Ω. I have no idea which colour is which. You need to measure the resistance between all three pairs of wires. I think that the primary side is the black-white-yellow side, but I am not sure. You need to check the resistance between black - yellow, and between black - white, and between white - yellow. You then connect the 220 V to the pair that have the highest resistance. It doesn't matter which way round you connect the live and neutral to the primary winding, but it does matter which pair you connect it to.
Then you can measure the output voltage.