First, you have to have set up the segue in your storyboard and give it the appropriate identifier. (Click on the segue (left panel) and then click on Attributes (right panel).
You can then link this to buttons or selection of table rows from your storyboard, or you can call it in code using performSegueWithIdentifier:sender:.
After this, your view controller will be sent the prepareForSegue:sender: message. You override this method in your view controller subclass, and can configure the target view controller as follows:
TargetViewController *targetVC = (TargetViewController*)segue.destinationViewController;
targetVC.string1 = string1;
And so forth. The sender in this method will be the object that you use as the sender in the original method call.