I want to find \$\frac{\hat{\theta}}{\hat{T}}\$
This kind of block diagram doesn't have anything to do with the rules for parallel and series connections of impedances. It just represents a bunch of complex algebraic equations. Each of the rectangular boxes just produces an output variable by multiplying its input by a constant, given by the text in the box.

For example,

\$ V_m = \gamma(I_{ref}-I_m)\$ comes from the first box at the upper left.

\$ I_m = \dfrac{1}{Ls+R}(V_m - E_{emf})\$ comes from the next box to the right.

You can keep making equations like this for each variable in the diagram. 
At that point you should have a complete set of equations that you can reduce to get a relationship between \$\Omega\$ and T.

To do this for a complex system like yours, you may want to polish up your skills in a symbolic math package like Maple or Mathematica.