php - Overriding Magento Admin Controller, for Beginners -

In the Magenta Administration section, I want to override the Core Dana's "Sales / Order / Shipment Controller.fp" Controller file .

I "from" & amp; Has tried to write the URL again; "To" tag, but in vain.
I do not know the real & amp; The right way to do this is because I'm a newbie in Magento.

Please provide some good fundamental to anyone; Correct answer, so that the least concept is clear.

Also, please tell me, what is the real purpose of the controller, both the frontend & amp; The end of the back?

Any help is greatly appreciated.

Not sure if you're talking about "from" and "to" tags ... what you need to do is write a simple custom module (best method), or give it to the controller / app / code / local / directory

[edit] - I wrote a post in which the various Magento elements were overridden, the controllers included:

I hope that helps .