Although i exactly know what OP is asking i would answer as per the query "how to install free apps...."
Simple go to app store and download the free apps, they are free right ? So no need to do anything special and device jailbroken or not does not matter.
Probably the question here is "How to install cr@cked and p1rated apps on my jailbroken device". I am not sure whether that should be answered here or not and risk infraction.