How do I use the JNI in c++?

Hi,
I am createing a dll that I want to use from a java program.
Ive generated my function definition,
now there is a couple of things I can not find information on.

In my function, I have a jobject (_jobject)
And jstring (_jstring)
I noted that these are classes as defined in the header file jni.h

How do I use these classes? I want to know use the string that was passed to me.

Does anybody know where I can find documentation on this, or a simple explanation maybe ?


Thank you, and I do rate answers :)

*BooM*