Need 301 Redirect

Hi,

I changed my permalink structure a little after I began my blog. Google still has indexed the old permalinks, and I’m afraid of being penalized for duplicate content.

You can an example here:
https://paintballguns.net/?page_id=8
and
https://paintballguns.net/ion-paintball-gun-review/

are the same pages. How do I got about using a 301 redirect method to avoid any penalities from Google?

Thanks!

Kyle