Transformer manufactures sometimes change color coding, so it’s always best to confirm the lead colors with the information you receive with the transformer.
That said, the general color codes for the secondary taps are: Red = B+ (high voltage), The red/yellow tap is the B+ center tap and goes to ground.
Green = 6.3v tap going to the heater circuit, Yellow – 5v tap, goes to the rectifier heater. Black = primary winding, connects to A/C source (120v in the USA). If there is no center tap provided for the 6.3v coil (yellow/green on the layout), then an artificial center tap is required to suppress noise is the heater circuit. That’s the two 100 ohm resistors you have added. If a PT comes with additional taps (and many do), do not assume that the multicolored leads are all center taps and wire them to ground. Unused taps should be cut off, cut shout or covered to ensure they do not contact anything.