Hi, you may need to use Simulink-PS converter to connect Simulink sources (in your case, it is a signal generator) or other Simulink blocks to the inputs of a Physical Network diagram (your circuit in blue colour line/ Simscape Circuit).
For more information, you may refer to the official documentation on "Connecting Simscape Diagrams to Simulink Sources and Scopes" at https://au.mathworks.com/help/physmod/simscape/ug/connecting-simscape-diagrams-to-simulink-sources-and-scopes.html
Hope this helps!
