First off

When I try and open a .dat file in omen to change the dimensions it gives me this error;

Creating new map...
Unable to find the level class. Check whether minecraft-server.jar is in your classpath.

Where do I put the .jar to make it work cause I don't know what a classpath is.

And secondly,

After I have the map loaded up in Omen, How do I change the dimensions of the map? I want to make it able to have active water and I heard that you need to have dimensions that are a power of 2. Since the water doesn't move (even using /activewater doesn't have moving water) I want to try changing the dimensions.

Any help would be appreciated.

Thanks,
Rellikz--