Hi Nish 86,
Its not that straight foreard. You can reside here in Namibia with your Namibian Husband with-out changing your current Nationality.
Marriange to a Nabibian does not grant Namibian Citizenship - just "the right to live and work here".
You can obtain Citizenship through Birth, Decent and Naturalization (living here for a long-long time, eg. more than 10 years.)