As an example consider an idealised/simplified model of butane, which has trans and gauche configurations as shown in the figure. We shall suppose these have different energies due to interactions between the protons on carbon $1$ and $4$ as bond C2 to C3 rotates.
We take the energy of the trans state at $0^\text{o}$ to be zero, $E_0 = 0$. The energy of the other two conformations, measured relative to this, have minima at $120^\text{o}$ and $240^\text{o}$ and are $E_{120}$ and $E_{240}$.
The partition function is the sum of the statistical weights of the energy levels. The statistical weight of a state $i$ with energy $E_i$ is the Boltzmann factor $\displaystyle e^{-E_i/k_BT}$, multiplied by the degeneracy of that state $g_i$. The partition function is therefore $Z=\sum_i g_ie^{-E_i/k_BT}$.
The partition function for our model butane is therefore $\displaystyle Z = 1 + e^{-E_{120}/ k_BT} + e^{-E_{240}/ k_BT}$. By symmetry, the energy of the $120$ and $240$ states are the same and the probability of being in either is $\displaystyle 2e^{-E_g / k_BT}/Z$ where $E_g$ is an abbreviation for $E_{120}$ and $E_{240}$. These two levels are accidentally degenerate.
Once the partition function has been found then the entropy $S$ can be calculated as can the internal energy $U$ and other thermodynamic quantities; $\displaystyle U=RT^2\left(\frac{d\ln(Z)}{dT}\right)_V;\; S=R\ln(Z) +\frac{U}{T}$.
If you calculate the conformational entropy you will find it is zero at low temperatures, because all molecules are in the lowest trans state, and rises to 3R at high temperatures.
Try not to think of entropy as disorder, it is generally more useful to think of it as the number of ways of placing the molecule in its many possible energy states.