What is the URL? Can I use the same URL in all posts before posting? Sometimes posting in meta site requires 150 reputations or URL REQUIRED. I never find and notice a URL. This is nowhere in my sight. Without a URL posting is not possible.
I assume you want to post a question on Open Source Meta, which is the site you're currently on. That requires 5 reputation, not 150, unless you want to ask a question about your own post on the main Open Source site. You can find the URL for that post in the address bar of your browser.
(that's how it looks like on another site)