When you search the library catalog and see an item you want to put on your list, you can add it in one of two ways.
If your search found multiple items, you will see something like this near the top of the page:

Click the box next to the title you want and then select ’Save to my Lists’.
OR...
If your search found only one item, you will see something like this near the top of the page. Click ’Add to My Lists’.

Either way, if you have more than one list, you can choose the list you want. Your item will be added to the list.