Adding supports to the model is achieved by specifying the Degrees Of Freedom settings for the nodes that will serve as supports. A value of 'Y' or 'N' (empty value = 'No') is indicated at the relevant nodes as follow:
Right click on any supporting node in the model
Choose 'Edit Properties' from the context menu
Use the 'Box Select' tool to select the supporting nodes in the model
Check the 6 boxes for Translation and Rotation (representing 'Fixed' supports)
Click 'Apply'
Press Escape to deselect all elements
Right click in the model workspace and click 'Update Model'
Display the support symbols by clicking on 'Show Supports' from the 'Model' ribbon tab