Can i use external DLLs?

i have an Class libry that i wrote in C# for some application i did in c# windows forms and now i want to move the application from forms to flash but i dont want to rewrite all the classes and functions.
i know that when i build the project in c# i get dll of the class librery.

can i use this dll in the flash and call his functions and classes? if so how???

i am totally new in AS3 (I know very good AS2) so can you give me the syntax of how to import the dll and how to call his functions?

tnx in a head (hhh)

maor