The main objective of the feature stapling concept is: Pre-activate desired features automatically on creating SharePoint sites based on site definitions like Team Sites (not site template .stp).
say for e.g. you want to apply branding on creating a team sites, You can use feature stapling.
So, In your feature, you have to handle the events such as “FeatureActivated” in order to run some code automatically on creating sites. In other words, place the code that should get executed inside the “featureactivated” section in your event receivers.
SharePoint Site templates, site definitions, feature stapling Check out my Presentation:
In case you need some help on creating features staplers, have a look at the below links: