I have a wireless printer but I can't print from my Iphone 4s or my Ipad.

Does your printer support Airprint?

You need to make sure that specific printer has AirPrint installed: http://support.apple.com/kb/ht4356

You did verify that your printer supports Airprint / ePrint, correct???

A wireless printer is no necessarily an AirPrint printer (most aren't).

Air Print Basics

http://support.apple.com/kb/ht4356

Also, unless I'm getting this confused with something else, your router needs to support Bonjour.

IOs devices can only print, through Airplay, to Airprint printers.

The are also apps in the app store that can help, but you will need to plug your printer into a wireless USB.

If you describe all your devices (IOS, computers and printers) then someone might be able to provide a more explicit solution.

Cheers

Bonjour? What the...

http://www.apple.com/support/bonjour/