It depends on what problem you are trying to solve. Look at the list at Introduction to Plugin Architecture#PluginTypes to understand more.

For example, if we want to execute the code after a form submission, then we can look at Form Store Binder, Form Validator, and/or Process Tool.

It depends on where is the trigger point, what is the return or result that you want - this will helps in determining which plugin type to use.

Cheers

Hugo

First of all you need to open your project in your preferred Java IDE, mine will be InjelliJ IDEA.

Next, create a new class anywhere in your package, to simplify things, try to create your new class (1) at the same package as the Activator class (this class is autogenerated and should be there). Then you just need to extend your plugin class (ex. SleepTool plugin) with the one of the abstract class from Introduction to Plugin Architecture#DynamicOSGiPlugin . 

You can see the complete codes here : https://github.com/kinnara-digital-studio/jw-plugins-async-run-tool

Regards,

Aristo

Thanku @Aristo