For bell, red wire of the 5906 to "A"(multi train transformers) or "U"(single train transformers) , black wire wire of the 5906 to center rail/lockon clip 1.
The remaining connection - from transformer common - "U"(multi train transformers) or "A"(single train transformers) to common/outside rails/lockon clip 2.
The 5906 should not be connected to common ever.