The psets have been rearranged a bit. The c programs that used to run through pset 5 are now psets 1 through 4, so yes, some shuffling has occurred. Speller is definitely pset4 now.
I would suggest that you move all your completed work to an archive directory, put your in-progress work on Speller in a new pset4 directiry and proceed from there.
Your username in the Terminal shell is ubuntu. This is true for everyone, regardless of what your Cloud 9 IDE username is.
Have you tried typing ls to list the contents of your home directory? It should return a list of folders, something like: