A real noob simple basic question, sorry about that.

I want a hex editor like HxD on Windows, I've done a search and come up with dhex. So I did the sudo apt -get dhex thing, all seemed to go well, but now what!? Where is it? I looked in /usr/bin yes dhex is there but now what? In Windows there's an icon to click, a new menu option to press, usually something obvious.
I went to Terminal, typed dhex and it seems to respond, does something relevant (shows help file) so I think right, I need it to open my file so I type: dhex myfile.mid - can't find file, so I try again with the path name; dhex /home/pi/mytests/myfile.mid and again can't find file.
Basic Linux stuff I know, what do I do to open myfile.mid?