The first step to call a workflow with parameters is to declare them in an External signal activity.
Open the External signal activity, then select the Parameters tab.
Click the Create element button, then specify the name and type of each parameter.
Make sure that the name and number of parameters are identical to what is defined when calling the workflow (see this page). Moreover, the parameters’ types must be consistent with the values that are expected.
Once the parameters have been declared, finish the workflow configuration, then run it.