what do I need else to be a professional web developer?by the way I know html, css and jQuery.

you need to learn new technologies and try to update your self with latest technologies most importantly need to clear your concepts of programming , your approach towards result must be clear , and you know which is the better platform for particular type of project which you are going to develop

Let me share you the fantastic resource by Rebecca Murphey "A Baseline for Front-End Developers" at http://rmurphey.com/blog/2012/04/12/a-baseline-for-front-end-developers/ Afterwards you feel yourself a distinguished and better Web Developer.
There is also a latest version of baseline available by Rebecca but go through after first one.
Hope you like it!

The fact is that you are not a web developer at all.
From those languages you know.
Because, what make you web developer is the ability to design a dynamic website by using a database and designing a web applications with the usage of PHP, ( or C#), colufusion - server language e.t.c May be you want to ask, how should I become a professional web design.
Then, with all those above languages, you are already on the way.
What makes anybody professional is how master and how frequency is using it.
Thanks.

you can call yourself front-end developer but that is not limited to CSS, Jquery step into CSS Framework, JavaScript etc.

for front end developer it's enough you just need to know some frameworks like bootstrap, foundation, and some other plugins.
if you want to go step further to back end developer, you need to know php and some php frameworks, now it's very popular laravel framework of php, and also you need to learn wordpress

You have to have a concept of programming and databases, this will help you to make we site with dynamic contents. You just need to leard basic programming and database concept along with latest tool of web site development in market. A huge market consist of open source development tool , like PHP or some else. The quick and best way to become web developer, you have to learn , Wordpress , or Jumla or any CMS . so that you will be able to design and develop your own dynamic site.

To be a pro web developer off course you need to know a programming language and start working with modules not in design section.

You need to know programming language like C#, java,PHP,....
and Sql