Not sure what bad advise Dick gave you that made him edit his post (so maybe I give the same) but I would:
1: Log in to cpanel
2: Scroll down to sections "Domains", click the "Redirect button"
3: Assuming the "http://(www.)?" field already have some text filled in (should be the domain name or as in my case All public domains), if it has text, skip the field after the / and go to:
4 redirects to→ and enter www.shatwo.com/thissideup in that field. Save and see if it does what you want.