After creating a series, follow the steps below to pin it to your navbar.
Step 1: Go to your blog's dashboard, and click on the "Navbar" tab visible on the left side panel.
Step 2: Click on the "Add an item" button.
Step 3: Select Series as the Type and choose the series to be added as the Value from the dropdown, as demonstrated below:
Step 4: Assign it a Priority between 0 and 999 to control the order in which it will be rendered on the navbar.
Note: Pages with higher priority numbers appear first, and others follow in descending order.
Step 5: Click on the "Save Navbar" button when you're done.
Step 6: Navigate to your blog, and your newly added series will be visible on the navbar, as shown below.