How to create independent/async processes for a website with user interactivity?

folks! I have just recently gotten into the back end side. And I've been struggling to figure out where to even start the last 2 weeks. I have basic php, javascript and mysql knowledge if that helps.

Explained in an image: Image .

I want to create a website where:

• users can create/edit/view processes
• the processes work 24/7 without needing the page to stay loaded
• real-time logs of processes
• processes have access to the database
• processes can be saved and survive restarts and server crashes

My questions:

1. What do I need to learn and use?

2. How do big companies do it?

3. Is there a simpler way for localhost testing?

4. How many methods are there and which are they?

via John Wannabe