i Do agree with Rupesh shingh Create custom module fully in sugarcrm is not a good approach until and unless u understand the complete flow !
for understanding the flow you can go through this :-
1)understand controller,views and how it we can use it
Hello module
And try to complete 2-3 chapter of this book definitive guide by John Mertic
2)create costume module from studio and first try to do customization with edit and detail view
Flow how customize edit and details view
3)After this try to customize list view based on condition and try to customize additional details popup add where clause default listview try to create you own list view Add custom button in list view to overwrite the list view search
4)go through chapter 10 of definitive guide by John Mertic which shows how to create custom module with out creating package in studio ( manually ) !
I hope this will help !!!