Are you talking about Windows the OS or windows as in a window manager / desktop?
If you're trying to start a GUI (graphical desktop), it's as easy as
If you're trying to open files in a Windows partition from Linux, your Linux OS should automatically mount that partition. I think (not sure) that it is usually mounted at /windows or something similar. You can browse there and easily open files and folders, edit them, and save them. Remember, however, that you can NOT open .exe binary files, unless using Wine or a similar utility. Even then, it's not guaranteed to run.