Light description needed

Well I currently have the Problem, that no matter what type of light and with wich values I create it it is never as I expected it to be:/ This is because I don#t seem to understand the different values I can set and in wich unit they are/(1 unit ingame is one meter for me, so if i set for example linear to 0.5f what will that mean?). Usually I'm able to get the lights I want them after trying around, but it's all try and error, wich is not a good solution.

It would really help me if someone could give me a few explanation how the lights in jme work and what the different values mean.

You could create a LightTweaker (like the ShadowTweaker) where you can adjust the different settings at runtime.

Well I currently use the Scenmonitor for adjusting, i have more or less the effect I want but I don#t understand the values and it is kinda ineffective if I have to trial and error every singe light I use(especially if not all are always present).

Had a look in the jME-userguide? Or is that not helping?

Maybe that helps. Otherwise you have to see what openGL says about this:

OpenGL Light - Creating Light Sources in OpenGL, Light Types (ambient, diffuse, material color and specular highlight).

What parameters are you unsure about? Ask away.