The request is sent to DNS server which will translate it into an IP address.
In case that particular DNS server can't find that IP address it sends the request to another DNS server which will then send that address back to the first DNS server which in turn caches it for future use and sends it back to my chrome browser.
The chrome browser on my laptop will then send the request to the facebook server having that IP address.
I then enter my login details through the facebook homepage which are sent to their database on their back-end server for verification, possibly using SQL, C# or Java.
If my login details are correct then I am logged in to my facebook profile page.
I then type my current status in the box on my profile page and click on Post.
The information is sent to the Facebook server and updated in its database using SQL, C# or Java.