Agile project management is about
- continuous improvement
- scope flexibility
- team input
- delivering products
which are all great things when it comes to developing web services in team. If you want to run a well managed project, read http://www.dummies.com/how-to/content/agile-project-management-for-dummies-cheat-sheet.html and follow.
On the other side of agile there is a waterfall style development. These two models have pros and cons. Please read, http://www.base36.com/2012/12/agile-waterfall-methodologies-a-side-by-side-comparison/.