Need help to install a NAVIGATION in my new Audi A6

[doki100]

Dear All, 

I would like to ask your HELP with my Audi A6 2005 DVD navigation. 
After I bought it I realised that the DVD head from the boot is missing and the NAVIGATION function is not working. 
I am ready to try to install the things myself but I need one of your experts help! 
I took as many pictures as it was possible to show you what we are exactly dealing with. 
I also find the DVD Navigation Player on eBay with the dvd. See on the first 2 pictures.

Do you think if I buy it I can install it? What else do I have to buy? And what are the tricky parts of the process? 

Please help. 

Thank YOU!!!!