Hi,
Since one cannot upload a PSD or TIF layered file with masks and all the Photoshops goodies here, I have found a way around. Please visit the following site:
http://juandentphotoshopproblems.businesscatalyst.com and press the button "Click to Download" to download the PSD
you will find a portrait where my intention is to replace the background. I have been using a mask and refine mask but I don't like any of the results so either my initial mask is bad or my use of refine mask is inadequate.
Please help!! Also if there is a simpler way to share a PSD, it woudn't hurt to know it 
Best