Web Services/references

I have several .NET books but am still confused about utilizing web services. My scenario is that I have a parent form that calls another form ( a dll ) that calls a web service. The web service accesses a database on a different machine. So, the parent app and child form dll are on one machine, the web service ( a dll also ) is on another, and the database on yet another. I made a web reference in the child form dll to the web service but this apparently isn't enough. What is missing?