HELP needed for good logic development

[razor2890]

Before any of you say that it is upto you to develop it just read....
I have an IQ of 187 and it feels stupid enough for me not to be able to put logics in loops in java language...
I learnt to speak manageable Tamil & Hindi in 15 days each & was fluent in a month...
BTW Tamil (& all Indian languages are very difficult to understand...) its my opinion..
I am about to learn French...

But I have spent 3 months in java & the best i could do is display patterns....sessions request in servlets....

Now, I am creating a shopping cart portal...
I got the main categories List,Name of portal, from database...




    eg:
    Category_id           Name                   Parent_id
    1                    Electronics                  0
    2                    Mobiles                      0
    3                    Books                        0
    4                    Computers                    1
    5                    Fiction                      3
    .
    .
    .
    so on..


Now computers should go under electronics...Fiction under Books... I got till Electronics Mobiles & books....But for Sub-categories i am stuck...

How do i get sub-categories into categories??
I was thinking of storing category_id in an array and search & compare it with parent_id of categories...
Even if what i think is write i have no idea how to put it in a code??Can anyone suggest  what i should do for perfecting Logic development in terms of code??Any learning tips or practice program tips??