使用codeigniter加载导航菜单

I'm new to Codeigniter MVC framework. I want to load navigation menu for each page. This is my nav menu structure and please tell me how can I use codeigniter to create this.

    Home 
    **Category 01 --Cat01-to 04 load from Database
       SubCat01
       SubCat02
       SubCat03
    Category02
    Category 03
    Category 04**
    Contact

You should using URI Class in codeigniter, and use suitable methods, like uri_string or segment_array.
URI class