What is Vc and Ve? Voltage-collector and Voltage-emitter?

Absolutely correct. If you have chosen current limiting resistors Rd for the diodes, then Vc can be found from the sum of voltages in the collector to emitter branch section......needs to sum to 12V.

12V = Ve + Vce + V_Rd + Vdiode

Vce is (Vc-Ve)

12 = Ve + (Vc-Ve) + V_Rd + Vdiode

Ve is grounded (0V) in this case. But the Ve in the above equation cancels with the -Ve anyway.

So 12 = Vc + V_Rd + Vdiode

So Vc = 12 - V_Rd - Vdiode

We usually know Vdiode. And we also usually know (by design) V_Rd, since we design the current through the diode (which also goes through Rd); V_Rd = I_diode * Rd.

Could also start from the collector..... with voltage Vc.

Vc + V_Rd + Vdiode must sum to 12 Volt.

So again, we get Vc = 12 - V_Rd - Vdiode