BPMN - Handling Condition only if success

I am exploring BPMN. i have scenario like, once task is submitted ,
1 . i need to check status variable (l1 approve -task) -if status=“completed” then move to end task ( process complete)
2. otherwise need to retain the same task(l1 approve)
3. How can i trigger the email if update the variable called in status ( example - whenever i am updating the varible, it should trigger an email) . How can i do that? please help.

Attaching jpeg image

You should consider following the tutorial videos. These basic concepts are explained and demoed in detail. It’ll probably help answer some of your questions

thanks a lot niall