The network wizard (located in the top right part of the Network view) should assist you in the completion of your mapping graph. It is a step-by-step process that should lead you through Adding a model, configuring inputs, adding a loss, adding metrics, and adding a visualizer.
An example of using the Network Wizard to complete a graph mapping
Then Network Wizard suggests to validate, update (i.e. save to file), or apply the mapping
Any issue in the current graph (for example, missing elements or connecting encoders to an incorrectly shaped tensor input), would be reflected in this wizard.