how to increment file pointer ....
suppose i want to read the 1st possition in the file and then the 64th position to do that??????????

You can use the fseek function:

int fseek( FILE *stream, long offset, int origin );

stream - Pointer to FILE structure
offset - Number of bytes from origin
origin - Initial position

The fseek function moves the file pointer (if any) associated with stream to a new location that is offset bytes from origin. The next operation on the stream takes place at the new location. On a stream open for update, the next operation can be either a read or a write. The argument origin must be one of the following constants, defined in STDIO.H:

SEEK_CUR - Current position of file pointer
SEEK_END - End of file
SEEK_SET - Beginning of file