Java fitting websites forms. Comilation problem

I have found many tutorials, which showed me how to connect with websites and fit some forms, but almost all of them contained small piece of code - without imports, I figured out that i need to use special library like htmlUnit or Watij, so I downloaded it, and tried to use but i couldn't. I have tried putting all jar files from downloaded zip archive to lib folder in java compile but it didnt work. I have also try to compile with -classpath - but it didn't work - probably I used it in wrong way, all time i m getting . Main.java:5: error: package [...] does not exist.

How can I add library to java compiler or how can I compile file with library properly.

I m using windows and jdk version: 10.0.1, also i m not using any advanced java editor like eclipse.

Thanks