I have put {$user_logging} in main_warning.html template, but this won't show up.

How can I make this work?

Thanks in forward.

Why would you need this for main_warning.html?..
It's the snippet for member's logged in status. Used in another templates!
It won't show in main_warning.html.

I want to approve new registerings, but after people are registering, they are seeing the thanks note, and after clicking the forums link, the warning that they aren't allowed to do this, shows up.
With {$user_logging} on the main_warning.html, I want to let the users know that they are logged in after registering.

So I was wondering if there was a way to show {$user_logging} on main_warning.html

You would start from a statement IF such question wasnt given earlier, instead of producing something really poor.

Here are additional instructions for closed registrations. Search manual and our forums before you waste time. If I am getting correctly what do you want.

Also, even in theory, users should not be logged after registering if you would like to approve them. Auto-logging makes no sense then.

I have solved my poor production,
and will not waste ur time anymore,
thanks anyway:)

It's not my time... it's your time...

I don't understand why you people are trying to do things they are not up to you at all.

Instead of just taking what's given and having fun with it, with no extra jobs involved, at least initially, you are trying immediately to CHANGE something, PROTECT from something, FORBID something, make it upside down completely, turning white into black and switching off the basics.

And when you exhaust at some wasteful attempts, you claim it's a bad software and switch to something poor and default-by-the-design like phpBB or SMF, which is not up to easy editing at all, no wonder.

Not about "you" exactly... but trust me... I've seen a lot in 15 years and all of such wasteful attempts are notable from the very first question on the forum.

The only question I have: why?.. why would you need to waste so much time with no blazing result?..
I couldn't allow it to myself...

As you say, adding many features doesn't mean that the forum is getting better.
I just want to change some behaviours of this script, that's all.

It's obvious you would like to do that :) My suggestion was about studying the current solutions and approaches, which are recommended regarding this script, instead of creating something, which will be not covered by easy updates and may be even insecure. In 15 years each new question like yours coming to this forum, in 95% is repeated. There's not only you trying to modify the software, and you have all rights to do this; my advice, however, is about that you do this properly to avoid problems and stay out of support.