Wiring is pretty simple. You should be able to wire using what I sent.The diagram shows four elements but id you only have 3, disregard the 4th element on diagram. If I have a pic it would be easy to mark them for you.
Here is what you will have.
1. White from thermostat to sequencer coil(Low Voltage)
2. Blue (common)from transformer to other side of sequencer coil(Low voltage)
3. Wire from breaker to M1
4.Wire from M2 to one element
5.Wire from breaker to M3
6.Wire from M4 to next element
7.Wire from breaker to M5
8.Wire from M6 to last element
9. Grey wire from fan relay also connected to M@ so blower comes on with first element.
10. Orange and blacks from breakers to other side of elements