Whenever you add a link into Wakelet, it is kept in your saved items.
On your saved items page you can select multiple items to add into a new or existing collection, delete the items or edit them. Keep in mind that if you delete an item, it will also be deleted from the collection it is in.
You can use the search bar and filters at the top to sort by item type, date added and oldest / newest first.
You can also add from your saved items whilst inside your collection. Simply open your collection in edit mode and click the 'Add from Saved Items' button on the right.
Notes and images will not appear in your saved items, but you can always access them by opening the collection they're in.