how to put username after domain name

[eluser]teddy[/eluser]
I saw some website deal/groupon can put username after domain name example: www.xyz.com/abc and in my website I want allow some users register nickname and they can post some deals/groupon they want and they access or views these posted by them throught out url like this: www.xyz.com/abc

Futher more how can I show a deal time with day, hour , minute decrease on web page with deal time decrease

Thank you for reading my topic