Help with capacitor circuit calculations
If we consider two capacitors in series







simulate this circuit &ndash; Schematic created using CircuitLab

Then we know \$ V_{C1} + V_{C2} = V_{tot} \$ but we have no way of determining how this is shared because lets say \$ C1 = C2 = 1 \mu F\$ and \$ V_{tot} = 300 \text{V} \$ for example then there is nothing to say the voltage has to be shared equally because one capacitor may have had some initial charge which makes this claim invalid.  Also since no current is flowing at DC the voltages across the capacitors will be dominated by the leakage resistance of the capacitors and not the capacitor values.

If we are assuming a purely theoretical answer then we can ignore leakage resistance and if we assume all capacitors were initially fully discharged we can assume that \$ Q_{C1} = Q_{C2} \$ since \$ Q = \int i \text{ dt} \$ and since all capacitors initially had zero charge and have had identical current flowing in them at all times since.



With that caveat in place the approach to this type of this problem is:


Calculate total capacitance (you have done this already).
Calculate total charge \$ Q = C{tot} \cdot V{tot} \$.
Calculate the charge in each series element,  they all have the same \$ Q = Q_{C1} = Q_{C2} \$.
Calculate the voltage across each capacitor \$  Q = C \cdot V \Rightarrow V = \frac{Q}{C} \$
Calculate the energy in each capacitor \$ E = \frac{1}{2} \cdot C \cdot V^2 \$