There are several ways to add your references to Zotero. How you do it, depends on your preferred methods, and if you prefer adding the references during your initial searches as you go, or afterwards.
After installing Zotero, your will have the extension "Save to Zotero", that will let you save references directly from your search at The Royal Library, as well as most other library- and databases. You may have to 'pin' the extension from the puzzle icon if you prefer having it on your toolbar at all times.
If there is one, and one one, possible reference on the browser page, saving to Zotero will happen with one click. If there are more than one possible reference (for example from a search result page), a pop-up will let you choose which reference(s) you wish to save to Zotero.
Like above, you can save reference straight from your search results, online articles and e-books by clicking the 'Save to Zotero'-button in your browser. This works from most sources, such as PubMed, Google Scholar, JSTOR, Springerlink and most other academic literature bases.
You can also save articles from online news media, just note that it will save as a 'website', and that the metadata is often not as complete as on journals and databases. Once you've saved the reference, you can add authors manually in Zotero.
If you've already saved articles as pdf-files to your computer, you can 'drag-and-drop' them into your preferred folder in Zotero. If the article has sufficielt metadata (from the publisher or source), Zotero will automatically create a reference from the file. If not, you can right-click and choose 'create parent' item and add metadata yourself, or you can find the article on the library catalog or Google Scholar, save the reference, and drag the pdf-file to attach to this reference.
If you have books in psysical form you wish to add to Zotero, you can search for the book directly from Zotero.
In the tool-bar, you can search from the ISBN-number (find it in the beginning of the book on the back of the title page) by clicking the 'magic wand'-icon called 'Add item(s) by Identifier'. Please omit any dashes or spaces - search for number only. Zotero will search for the book, and if possible, create the reference.
Special types of references such as podcasts, dataset, letters, blog-posts (like posts on X, Instagram or Facebook) can be added manually. Click on the green plus-icon, select material type, and enter the metadata manually. You can also save them as websites, and then change material type and add missing information manually.
Conduct your search in an OvidSP database: Embase, International Pharmaceutical Abstracts, Medline, etc.
Click "Export"
Choose format, either "Endnote" or "RIS", RIS is easiest to import in Endnote.
Under "Fields" choose how much information you want to export.
Click on "Export" and save the references
The references are saved in cgi or RIS format, and must now be opened in Endnote.
RIS files can be opened directly.
CGI files must be associated with Endnote the first time you use the file format.
Do your search in the library system: https://soeg.kb.dk
Click on a title or 
Select RIS (Endnote, Mendeley)
You must not change or select character sets.
Click "Download" and save the file.
The references are stored in the RIS format.
Open the file and import the reference to Endnote.
Check the information in the fields "Edition" and "Place published" in imported book references.
In Endnote, in the menu click on "File"
Select "Import" and click "Folder.
Find the folder that contains pdf files and import them.
Not all PDF files are imported correctly and it may be necessary to import them from a database instead.
It is not possible to download all references from databases and some must be added manually. This applies, among other things, to websites.
In Endnote click on "References" in the menu and select "New reference"
Select "Reference type" so that it matches the type of material you want to reference
Not all reference standards have defined all material types.
The primary types are: Journal article, Book, Book section (chapter) and Web Page.
Fill in the relevant fields.
If a reference is missing author, publisher, place of publication or year, you can fill in the field with:
Example of a website
Note the three date fields. They are used differently by different reference standards, so it is best to fill in all 3.
The date formatting may vary depending on which reference standard you use:
Finish by saving the reference. In the menu click on "File" select "Save".