If you have never worked before with these types of cameras, you should first consider how you should get the film in the holders, and how to develop the film. Did you do any 'research' on that aspects yet?

Btw Contessa Nettel wasn't part of ICA (ICA was formed in 1909 as a merger of Hüttig, Wünsche, Krügener and Zeiss Palmos). In 1926 Zeiss Ikon was formed as a merger from ICA, Contessa Nettel, Heinrich Ernemann, Goerz.
Therefore Contessa Nettel had there own line of plateholders which are not so easy to find.

You can also find some info in the Rada catalogue (Rada made plateholders for all the different German cameras):
http://www.fotografische.de/wp-conte...fische_de1.pdf