Hello @roy0621,
To add a sidebar menu navigation, follow these steps:
1) Go to Appearance > Editor in your WordPress dashboard.
2) Open the template (e.g., Page or Single Post) where you want to add a sidebar.
3) Inside the sidebar column, add the Navigation block to create a sidebar menu.
For further assistance, please refer to the screenshot below:
https://ibb.co/TvC192j
Thank You.