CompuServe Messages

Could any one help me out. I have a friend who has an Amiga 4000/40 he is an elderly gentleman in his late 70's and is house bound. He would like to join compuserve and be able to communicate with the world. He has asked me for advice on how to do this using his Amiga, unfortunately I operate a PC and know nothing about Amiga computers. I need information about the software needed, I assume that any good modem will do ? Thanks Tony Shields