printf("%c", Character);

Means, "print the character having the ASCII code value given by Character"
ASCII code 9 is HT (Horizontal TAB).

Character = '9'; 

Means, "Assign the ASCII code value for the character '9' to Character"
The ASCII code for '9' is 0x39,
The ASCII code for '8' is 0x38,
The ASCII code for '7' is 0x37...
get the idea?

So, to convert an integer value 0..9 to its ASCII character code, just add 0x30

With the aid of an ASCII table, you should be able to work out how extend this to convert an integer value 0..F to its ASCII character code.