How to add extensions that developed as modules in yii? can any one explain extensions as Yii modules and extensions as Yii behavior
The first part of your Q is a duplicate with this q: https://stackoverflow.com/questions/12008314/modules-in-yii-explain
regarding the "How to Use Modules" part. Modules are may be the easiest way there to extend yii, since all you need to do is two tiny steps:
/protected/modules
.return array(
...
'module' => ('moduleName', 'some argument', 'another argument'),
...
);
I haighly recommend taking a look at the docs above then User-Module (as code sample) to get a better understanding to yii modules.
As for "Extending Yii by Behaviors", i have been confused myself for a while about that, until i had a chance to use the Multi-Lingual_Behavior
There is no typical way for extending Yii with behaviors, simply because there are multiple options (as you can see in the docs here & here) for using (attaching) behaviors to components (application, models, controllers, ...etc)
That said, most of yii-extensions there are supported with good Usage
docs that are enough in most cases to get them working.