You have to set the osbot.jar to your external path whenever you create the project.
On top of your script you have to import the classes in the API, example:
import org.osbot.rs07.script.MethodProvider;
import org.osbot.rs07.script.Script;
import org.osbot.rs07.script.ScriptManifest;
If you got that set you can start of by writing your script, your first line should be:
@ScriptManifest(name="scriptname", author="name", info="", logo="", version=1)