How to add external library properly in Eclipse?

Use maven

You don't have to download all jar's into a folder by yourself! - use maven. It's based on a public repository, and you manage your dependencies in an xml file.

Your project will have a pom.xml file that going to look like this:

<project>
  <modelVersion>4.0.0</modelVersion>
  <groupId>com.mycompany.app</groupId>
  <artifactId>my-module</artifactId>
  <version>1</version>
</project>

and in this file you manage the external library dependencies

for instance, if you wish to add this dependency - http://mvnrepository.com/artifact/org.apache.commons/commons-lang3/3.4

you will need to modify your pom.xml like so:

<project>
  ...
  <dependencies>

    <dependency>
        <groupId>org.apache.commons</groupId>
        <artifactId>commons-lang3</artifactId>
        <version>3.4</version>
    </dependency>

  </dependencies>
  ...
</project>

and save it. that's it

• Read this getting started tutorial - https://maven.apache.org/guides/getting-started/
• eclipse plugin - https://maven.apache.org/plugins/maven-eclipse-plugin

You must add jar file on lib folder and then right click on jar file and click "build path"-->add to build path and now you can write that jar file code

Recommendation:

1. Create a "lib" folder and keep all your jars in the folder.
2. Subsequently, add all the jar files in the lib folder into your build path by using Project => Properties => Java Build Path => Libraries => Add JAR ...

btw, there' no screenshot. Can you give the link for the screen shot so that I may be able to help our better...