Implementing macro processing in C

Question

I am trying to write a program that acts like the standard preprocessor (I don't intend it to be as vast and deal with all limit cases, but in principle). I have already done the #include processing, and #define without args, but I don't know how to deal with the argument of the #define.

The question is about implementing macros with arguments.

So I have this node I built after reading the statement: #define add(a,b) a+b

struct list
{
   name:          "add"
   defined name:  "a+b"
   next adress:    17204(adress of next node in the list)
}

And now I got the call in main(): add(2,3). So I go into the above node, and somehow the x+y should change into 2+3, as read by the argument. And then past the altered string.

Please give me any suggestion, you can add data to the the node if needed.