  An approximate procedure for performing nonperturbative calculations in
quantum field theories is presented. The focus will be quantum non-Abelian
gauge theories with the goal of understanding some of the open questions of
these theories such as the confinement phenomenon and glueballs. One aspect of
this nonperturbative method is the breaking down of the non-Abelian gauge group
into smaller pieces. For example $SU(2) \to U(1) + coset$ or $SU(3) \to SU(2) +
coset$. The procedure also uses some aspects of an old method by Heisenberg to
calculate the n-point Green's function of a strongly interacting, non-linear
theory. Using these ideas we will give approximate calculations of the 2 and
4-points Green's function of the theories considered.
