Cutting Images Better?

Is there anyway to cutting images and getting them right is there any post about it cuz i forgot how to cut again and i want to start doin it again but i just cant remember how to like what to do so if anyone could help me thx.

 

Here's a rendering tutorial by kazuya

http://www.deviantart.com/deviation/25884841/

 

Uhmm i have a question what if i want to delete the part of it and instead of it going to erase it how come it puts black in it like it fills it in??

 

Copy the image you want to cut, go to New and set the background option to transparent.

 

Make sure your pen tool is on this mode:

 

Thanks for tutorial btw.