Links
External link is general web link targeting some external web resource - e.g. https://en.wikipedia.org/wiki/South_China_Sea is an external link to one Wikipedia page.
External links are done through CKEditor native links. To create an external link, select text and press CTRL-K or wait for the "balloon" to appear and click link icon there.
You can follow external link by either double clicking (will open new tab/window) it or right clicking on them and choosing "Open in new tab".
Links to internal notes are created a bit differently. To create link to note at current cursor position, press CTRL-L.
In the dialog you can see radio button to choose from different types of linking. First one is classic link to note, the other two are related to cloning and will be covered separately.
You can follow the note link by double clicking it.
Alternatively if you only wish to quickly preview the content, you can hover over the link and will see read only preview.