Jailbreaking and deploying on iphone3gs using ios5

First jailbreak using latest version of redsnow : 

http://osxdaily.com/2011/12/27/how-to-jailbreak-ios-5-0-1-untethered-with-redsn0w/

Then follow these instructions to run/deploy your app on your iphone : 

stackoverflow.com/questions/246422/how-can-i-deploy-an-iphone-application-from-xcode-to-a-real-iphone-device