Often the reason people make those kind of comments is because working from the command line is best done when someone actually understands what they are doing (rather than just following instructions blindly, which is obviously dangerous) and that requires some minimum level of self-sufficiency and willingness to "RTFM" (as the saying goes) above the expectation that basic command line utilities will be spelled out here when there are myriad online resources clearly explaining same.

For example, Rob1n gave you the tools to diagnose your current problem rather than giving you a specific answer about why it probably occurred. I'll give you the additional clue that when you first open an xterminal, your working directory is by default your home directory, which in the case of the N900 is /home/user/. That's not MyDocs. You'll need to change the working directory to MyDocs.