Recompiling my DLL as SO.

Hi everyone. I have a Unity3D game that uses some C++ scripts as DLLs. I would like to rebuild the game for Android, but as I understand, android does not accept DLLs and I need to recompile my C++ script as an SO file. (Did I get that part right?).

Problem is, I have no idea how to do that. Could anyone point me in the right direction, in terms of what program do I need to do that, and maybe show me a good tutorial for that?

Would I need to change any of the script, or is the SO format similar to the DLL format?

(as of now, I'm using Visual Studio to work with my C++).