How do I import:
First of all, you should have a Project. Right Click Eclipse Project from the Project or Package explorer
Properties -> Java Build Path -> Libraries
From here select:
Eclipse select menu: Window -> Preferences -> Java -> Build Path -> Classpath Variables
Select New and give a Name and select a file or folder
Eclipse select menu: Window -> Preferences -> Java -> Build Path -> User Libraries -> New
Provide a name and in that you can add jars from within a project or from the file system just like how it is mentioned above.
NOTE: In some cases, it might be convenient to allow build tools like gradle or maven or ant with ivy to manage your dependencies for a project (when i mean dependencies i mean libraries) as some project have about a few hundred jars as dependencies, and manually managing them might be painful. These build tools have the functionality of downloading the jars and its sources for you automatically by just adding an entry in a file and even caching it for later use.