You can add Items to the Catalog that will be accessible by anyone in your org. Refer to How to Create a New Item in the Catalog?

To edit Items that you have added to the Catalog follow the steps below.

Step 1: Navigate to the Catalog at the top of your screen.

Step 2: If your Item has recently been added, you will see it in the recent Items which appear automatically when first accessing the Catalog. If your Item is not recent, you can use the search bar to locate it.

Step 3: Click the Item name to open up full details for that Item.

Step 4: Select the Edit button (pencil icon).

Step 5: Edit any attributes, and click Save.