1. You need to add statuses to Jira.
2. You need to add the created status to your workflow.You can read more here about it
If you are taking about boards then after adding new statuses to the required workflow you need to configure columns for you board. You can read more here
I did that but still, can't see the statuses. When I return to edit workflow, the workflow appears again as draft even though I published it.
1. Do I need to do something with the transitions in order for it to work?
2. It is written for this workflow under the headline: "This workflow is managed internally by Jira Software. Do not manually modify this workflow." This means I can't publish it?
I see, Go back to the workflow and create transitions between statuses. For example, you would need to create a transition from "to do" status to the new status. You can read more here
Go to Workflow designer part
There are some restrictions on workflow editing. Copy the workflow. Make all changes to the copied workflow and then associate it with the project workflow scheme.
Read here about workflow limitations
I guess you limitation is
I guess your issue is in the Open status. And there are only 2 transitions which go out from the status. I guess these are the two transitions you can see on the screen. If you execute one of the transitions, then your issue will move to another statusand you will see only transitions which go out from the status.
Open your board. Then go to Board->Configure and choose General (it is chosen by default). Then you will see there Saved Filter option. Click Edit filter link and look at the JQL query. If you can not figure out why this JQL query does not return your open issues then paste your JQL query here.
I some how managed to activate the workflow (or the workflow scheme, I got lost there).
And now, in my project I have two problems:
1. For each issue, I want to change the current status to the new statuses I have created but I still can't:(:(, I can only change it to a transition (picture attached), why is that?
2. Everything disappeared from my backlog. why?
It astounds me that people think they can work with a tool like Jira with zero training or reading of documentation. All of these questions are answered within the first few (VERY FEW) pages on Workflows in Jira's documentation.
First, it's best to start by cloning your workflow so that you can work with a separate copy of it first.
Second, at the VERY LEAST you MUST learn what Steps, Statuses, and Transitions are. If you refuses to research this, then I'm not sure anyone can help you.
Finally, you should be trying this in a test project so that you don't interrupt your existing project. Blindly editing a workflow when you don't know what you're doing is just asking for data loss.