How to add the classes which are designed by me into java library ? (to use "import" keyword in other classes )

How to add the classes which are designed by me into java library ? (to
use "import" keyword in other classes )

I want to use the classes which I designed separately and I want to add
them into a java library to use them in other classes with import keyword.
How can I do this?
Also, I should explain that I copied the classes folder in the zip file
which its name is "src.zip" at "C:\Program Files\Java\jdk1.7.0_25" but
when I use the import keyword in the IDE it seems that there is not any
folder with that name in java library.