You'll need to create a list or library to store the information about the services. You can use any of the pre-made templates or create your own. Once you have your list or library set up, you'll need to add columns to store the information about each service, including the name of the service, a description, pricing details, contact information, and any other relevant information. Once the list or library is set up, you can add services to the catalog. You can add services one by one or bulk upload services from a spreadsheet. Then, you'll need to create a permission structure so that users can access the service catalog, like setting up groups and roles, setting up access control lists (ACLs), and creating workflows for service requests. Finally, you'll need to create a user interface for the service catalog to allow users to easily search for, view, and request services from the catalog.