I believe you mean "tau method". If so, for an overview have a look e.g. in the Springer's Encyclopedia of Mathematics (link attached) and choose a specific method depending on your problem (e.g. numerical solver for boundary value problem for nonlinear ordinary differential equations).

http://www.encyclopediaofmath.org/index.php/Tau_method

I have a Mathematica notebook that illustrates the method for a nonlinear ODE ( PDF version also available). Go to the following site: https://sites.google.com/site/ekayasolutionsdiffeqns/home

and check the notebooks/PDFs under the spectral collocation section

Thanks it helps

I really appreciate all your concern. Thanks very much