Q: How do I print from iPad mini

Printing is built into the iPad's operating system, it is called AirPrint, the question is, do you have a printer to which the mini can print?

http://support.apple.com/kb/HT4356

Which app are you talking about?

If you don't have an airprint enabled printer then a printing app is good, if there isn't one from the printer manufacturer such as hp's eprint then you can try another app like printcentral

I have downloaded AirPrint and have a Epson Artisian 837 Printer.  I have an email on my screen but do not know how to command the printer to print???

What do you mean that you have downloaded AirPrint?

Print is found in the share menu of the application.  If you have an AirPrint enabled printer, that is on your network, it will just show up.  Pick it and print.