You may post articles on any topic of your choice. It would be better if you post an article on the topic on which you have a good hold.
Since this is technology based website, I would assume you will be comfortable writing articles on tech topics. For example, you can start writing reviews of some smartphones or laptops or even PC games. You can write "how to" articles related to Windows 10 or Android One phones. In simple words, just write on any latest technology gadget, software or hardware that is in the news recently. Good Luck! I am sure you would do well.
Thanks & Best Regards,