Hello and welcome to armaholic.
Arma is a very special, mod-friendly game, but you need to do things right if you´re going to modify it. Take a look at the FAQ
to learn how mods should be installed "correctly" (by this I mean not overwriting any of the original BIS files) using the "folder method". Now for the part that should interest you the most. To be able to use an addon in MP, the server has to be running such mod, i.e.: if I want to play with the OKT noBlur mod, both the server and my machine have to be running the mod. As far as I know for the DayZ mod, you´re not allowed to further modify your gameplay experience, this meaning you can only
run the DayZ mod and no other more. Hope I could help you a bit. I would wait to see if someone with a bit more of experience posts here as I could be wrong in some of my statements. And for questions about the DayZ mod, try it´s official forum, I bet you can get lots of support there