How can ι create my own (custom) WordPress table/list?

I’m not an expert on this but I did get into it a little recently. Take a look at this tutorial: http://wpengineer.com/2426/wp_list_table-a-step-by-step-guide/

Basically, you’ll want to create a class that extends WP_List_Table:

class My_List_Table extends WP_List_Table {
   // what your table is all about
}

$myListTable = new My__List_Table();

It is an involved process, but that tutorial seems pretty good. Good luck!