How to write a logging program for a web server

I have not programmed for a web server before. This will be my first, simple but highly useful to me, web application.

I have 100 sensors around, all connected to Internet. They will send every 5 minutes, one line of text including an id, a time stamp, a few numbers.

I imagine they all send to the same server, on which this web application will log the incoming text. It could be in a flat file or a proper database. That's all.

How do I start? (1) Which Qt classes should I use? (2) Which textbook or other resources could introduce me to writing this kind of web application?

This sounds more like a task for web service than web application.
AFAIK there is no framework in Qt for building web services.
But have a look via google, Eclips has a full development environment for building WebServices, and there are a lot of tutorials around the net.