This question is in reference to Atlassian Developer Documentation: Create a HelloWorld Plugin Project
How to create JIRA plugin. and how to install the plugin in JIRA cloud. i need basic concepts on plugging designs and codings
There are two types of add-on you can write - type-2 and Connect. You can not install type-2 add-ons in Cloud, it only supports Connect add-ons (plus Atlassian's approved list, which is not taking new add-ons). You can not install Connect add-ons in Server versions, it only supports type-2
You have named a tutorial for a type-2 add-on, but then asked about installing on Cloud. This is quite a common error for new developers, but I'm really not sure how Atlassian could improve their docs to make it more clear.
First, decide if you're writing for Cloud or Server, because that determines which sort of add-on you need to write.
If it's for Server, then the tutorial is good, and you'll find installation is just a case of "upload add-on" after you've built it.
If you're building for Cloud, follow Aleks' link (and forget the helloworld tutorial)
Connect with like-minded Atlassian users at free events near you!Find an event
Connect with like-minded Atlassian users at free events near you!
Unfortunately there are no Community Events near you at the moment.Host an event
You're one step closer to meeting fellow Atlassian users at your local event. Learn more about Community Events