How to add external class folder to play project

[ravi nambiar]

Hello 

I have a folder which contains some class files that I want to use 

in my project.   (Play version I am using is 2.4.x)

Things I tried : 

copy the class folder to "lib" folder and when I compile it gives error specified path not found.

Where should I specify the dependencies and how?

Regards

Ravi