Wanting to code in a custom placeworker

[SlimeCrusher]

I'm starting to look into DLL modding, starting with something simple. I want to make a building that you can only build on water, to generate power. But i can't really find any way to do this, i've tried a placeworker, they always seem to reference things though (and when i tried making a test placeworker referencing walls, i broke the object, even though i only changed a single word... whoops?). Is there any way to make it reference terrain instead of things?
To clarify, i don't have any experience on c#, so be gentle 

[1000101]

Well, CCL already contains those place workers.  You could (a) look at CCLs place workers and how they work or, (b) use use CCL for the "generic" stuff like this so you can save your efforts for your mods specific needs.

[SlimeCrusher]

Well, seems like C# can wait a bit then, i have a lot of experimenting to do with CCL :p
Thanks!