I have Domain Mapping installed and working but cant 301 redirect old static URL

URGENT HELP needed: I've tried everything (plugins and .htaccess code) but don't know how to put in 301 Redirects for an old site page to the new Domain Mapped Multi-Site: i.e.

Parent domain: http://www.lancasterhomes.ca

Child site:

http://www.lancasterhomes.ca/simcoelandingkeswick/

Mapped Child Domain:

http://www.newhomesinkeswick.ca (DNS has been changed to point to Parent IP, Domain Mapping Working)

Want to 301 redirect
http://www.homesinkeswick.ca/community-about.php TO

http://www.homesinkeswick.ca/the-community/

How is this done? Thank you!