I'm going to assume you don't have any bankground knowledge in any coding languages because you think it is simple.
If you want it in a .dll you have to set it up properly and then compile it.
I suggest you try to learn about c++ before just jumping in and trying to create something.
Their are some good tutorials in the c++ section and source codes found on google.
I may give you some help if you add me on msn (located in signature) but I'm not going to spoon feed you.