Hello, Anh!
The basic tasks can be performed by changing the module widgets.
You can change the screens a bit in order to achieve simple functionality. Ther module builder also
provides a way to set some validation. Here is a good place to start:
http://www.sitefinity.com/documentation/documentationarticles/user-guide/website-content/creating-and-using-custom-modules/editing-the-module-and-the-module-screens
Complex logic needs some development. Checkout the Sitefinity documentation for more info on this.
We will soon start our blogs (
http://eveliko.com) where there will be some walkthroughs on how to perform some end user tasks with Sitefinity so be sure to check us out the next week.
Disclaimer: eVeliko is not connected to Telerik in any way other than being a partner and a publisher to Telerik's marketplace.
Mentioning this to let you know that by saying "we" I refer to eVeliko.