BAYES-LIN is intended for people who already know about Bayes linear methods, graphical modelling and local computation, and want a collection of object-oriented programming tools for carrying out computations. Local computation in BAYES-LIN is achieved via message-passing between objects representing clique-tree nodes. If you are relatively new to Bayes linear methods, then I would suggest trying out [B/D] before experimenting with this package.
BAYES-LIN is a set of modules for the XLISP-STAT statistical programming environment, and hence assumes some familiarity with that system, and the basic concepts of object-oriented programming. It also pre-supposes that you have a working LISP-STAT system already installed.