I have a dataset consisting of 5 classes and the prior probability is $p(\omega_c)=\frac{|D_c|}{\sum_{i = 1}^{5}|D_i|}$. Suppose each class $c$ associated with the likelihood $p(x|ω_c)\,=\,\text{N}(\mu_c,\Sigma_c)$.
How can I derive a decision rule using Bayes' rule to assign a sample to one of the 5 classes? Moreover, how can I calculate $P(\text{error}|X)$ and $P(\text{error})$?