Hi Pedro,
I agree with the replies so far. 301 is the best for SEO.
If you already have a .htaccess file then just put one more line into it, similar to the following
redirect 301 ./my-page.html http://www.mysite.com.au/my-new-page.html
If you don't then just make a plain text file and name it .htaccess, put this code into it, and then ftp it to the root of your site.
It will all just work like magic if you have an Apache server or similar. If you have a windows server or something else, then you may in for some more legwork to get the redirect to work.
This is the best approach for non cms websites. For websites like Wordpress you have many more options available through plugins... Yay...!
HTH