metasploit is a great tool, but I have never been able yet to perfrorm a successful exploit because of my internet security program (Kaspersky). There are tons of tutorials to be found on the net about Metasploit, but none of them works without disabling Kaspersky.

What I want to try is to donload a working exe from the internet, for example Skype, and inject this exe with the payload, and encoding it so it goes undetected.
I tried to do this by altering the .text and .data parts with a PE editor. I added 500 bytes and made the .text executable and .data writable. Then I added 500 nullbytes with a HEX editor and tried to encode it. It says 'no encoders succeeded'

I think I'm a bit on the wrong track here, but I can't seem to find well-written explanations about this. It is always assumed that you have an encodable .exe. But what if you have not?

I'm not really asking for a complete tutorial, just point me in the right direction and i'll be happy..

(you can go hard on me if im completely wrong in my thinking)