I have a knowledge of HTMl,PHP,SQL and have been designing websites just as a hobby.

What I want to try out now is mobile web app, and my preference is on social networking like 2go,Qeep etc.

My first preference will be for apps that run on java phones. What I need now are tools(softwares) and links to tutorials to help me get started.

ya,
U can do it if only u ARE determined to do it.
I wish u success in ur endeavour.

Your approach will depend on your level of skill,an approach that will get you running with your skill-set is to develop it as a web app.
I'm assuming you had good familiarity with the web-dev stack, if you don't, well, do. So I'd break it into two category of which you can then further investigate

[Front-end: HTML(5)/CSS/Javascript -- will mostly handle your presentation and those fancy buttons]
Sancha (HTML5 based): http://www.sencha.com/products/touch/
JQTouch: http://www.jqtouch.com/

[Back-end: PHP/MySQL]
Ok, I should note here that all this I will be describing require you have solid (or at least a passing) knowledge -- I mean, if you can't tell what any of this is by just see it, open Google and read up on them before proceeding at all.
1) Object Orientation 2) Design Patterns esp. a) Active Record (AR) b) Object Relational Mapping (ORM) c) Model View Controller (MVC) d) Singleton. e) Factory

And of course, how they relate to PHP language using MySQL as the DB. That done:

There are a ton of PHP framework, but this, I've found shine; you of course can read their respective documentations to choose:
Kohana: http://kohanaframework.org/
Yii: http://www.yiiframework.com/

------ OR --------
You can download pre-made solutions and be another chicken a.k.a "installers" which it turns out, Nigerian web dev'er are getting the rep of being lately. I unfortunately cannot recommend any.