I am new to Inkscape but am vaguely familiar with it (I used Illustrator back in high school). But I am having some trouble with a few simple things.

With this image I would simply like to separate a portion of this image

......to look like this (done with paintshop eraser)
but I can't seem to get the nodes to separate the conjoined black. This probably is a very stupid question but any input is appreciated.

thank you,
Joel

I got it!

So after reading through the manual for a few hours, I figured out how to use the erase function. I now realize there are 2 modes with the eraser - eraser touch mode, and eraser cut-out mode. The touch mode will erase the whole object it touches, the cut-out mode will erase just the line that goes through it. I used the cut out mode and then erased all the excess nodes, and then was able to shape it to my liking.

Inkscape has an eraser that works quite well - as long as you don't ask it to do too much Did you try it yet?

Aaaah...I'm always forgetting about that Eraser tool -- I should use it more often!
I usually would do node editing in that situation: 1 - break path at nodes (or between nodes); 2 - Path menu > Break apart; 3 - join nodes to close both paths (or join with new segment)

Druban - I did try it and it worked great! It leaves a huge amount of nodes but I learned how to erase them. Thanks for the excellent graphic demonstration.

Brynn - Thanks for the info on the 'break apart' option. I knew there were some kind of option like that to join the nodes but had no clue where to start. I will give it a try next time.

I would draw a thin rectangle (or a more complex shape using if necessary) which covers the material to be removed, then Path=>Difference to perform the cut. Optionally followed by Path=>Break Apart as per Brynn's method.