Use VB Code To Create A File?

At work, we need to keep track of our new clients and until now we haven't had a good way of keeping track of them. I am creating a program so that we can just enter in the client information and have it save it to a file that can later be printed. I don't know how to save the information from the text boxes as a new file. Below is a picture of the window that will do this.

When the "Add Client" button is clicked, i would like it to add that information to a file so that we have a complete list of all our clients. What code do i need to use to have it save that information where I want it?