I am no graphic artist, but I think it would behoove you to search for guides on how to do this in the GIMP and even in PS. The techniques should translate pretty well to Krita, different though it may be.
Not to be a jerk, but given the report you've attached, it wouldn't hurt to install the debugging symbols for Plasma. They're available in the repos, and should make your reports way more informative for anyone reading them. =/
Quoted from "zephyrus17" I have ntfs-3g and stuff, because I could read/write my other external from gnome/nautilus. Well, have you tried using GNOME/Nautilus to write to this particular drive? It doesn't sound like a permissions problem, but definitely check that. Try chmod 777 just for good measure (then make sure to change it back).