@silviurec you should have two set of wires. One set Red/Copper and the other set Green/Copper. Red wire is Right Speaker + and Coper is Right Speaker Gnd. Green wire is Left speaker + and copper is Left speaker ground.This is where you need to connect the wires to:
Left = Tip
Right = Ring
Ground = Sleeve Both of the Copper wires get soldered on that pin
Something that looks like this will work for your headphones.
[image|3230840]
img from [https://rhondajones.top/|here]