Photoshop - extraction tutorials?

I was taught to do all the work in capturing a good photo and not fix things in the darkroom, so when it comes to Photoshop my skills are still developing

Anyhow, got a lot of the basic controls ok from books and playing (and guidance from folks here) but I am now bumping in to my own limitations - it may be that you want to stop reading now and just point me to some good on-line tutorials (believe me I have looked and wasted plenty of time searching)

Lets suppose I have a colour portrait going to high key black and white. Already took it to b&w via channel mixer layer to background copy, added a curves layer, did some burning - all okay so far. In capture the background wasn't quite blown out and I am struggling to select it to do this as there is a graduation across the image

Worse case would be to erase it by pixels or something but I have several to do and want to learn how to do this "properly". So how to extract the background quickly and easily?

It sounds like you are having trouble with a selection firstly. One tool that is useful is the 'Magic Wand' (looks like a fireworks sparkler) - it will automatically select areas of same colour and brightness as where you first click - the trick is after the first click then use a right-click and choose 'similar' from the context menu. This should then grab all the same tones you're needing.

For tricky extractions then plug-ins are best - try Topaz ReMask .....
http://www.topazlabs.com/remask/

Nigel