I am planning to create a small software. I have 3 structures and 2
data files in the design of a small CD Library rental.
Say the number of CDs are below 500. They are nested structures.

1) CDList which contains the number of CDs and a CD structure. 
typedef struct cdList
{
   CD cds[120];
   int count;
} CDList;

2) CD structure contains details of CD and a Sale structure. 
typedef struct cd
{
   int id;                     // CD id
   char title[40];          // CD title 
   char director[40];    // directed by 
   float cost;              // rental 
   int count;              // no. of. cds available
   int rentCount;        // no of rentals
   Sale sales[100];
} CD;

3) Sale has details of the CD rentals. 
 Rentals / Sales
typedef struct sale
{
   struct tm date;     // time and date of sale
   int quantity;         // no of CDs sold
   float price;           // cost of book x quantity 
} Sale;

I have the following things to do 
1) Load the data from files
2) The following functions are used which all has argument a pointer
to the CDList structure.
- Display 1) CD List and  2) Sales
- Search for a 1) particular CD  2) Sales
- Make a rental
- Add a New CD title

Hows nested structures implemented with pointers?
The data is read from 2 files?
Files used are 1) CD.txt 2) Sales.txt

I know C in bits and pieces. So I thought of asking help in the answer
forumn. 

I would like to have the code for the program so that I can edit those
and i will be getting some experience in C programming. Please
help me in creating the software.

This looks like 'homework' to me

I can assure you that the approach you describe is totally
inappropriate to a real life application.

It is 'painting yourself in a corner'.

See I am doing my own business. And I wish you guys help me solving this