what is the correct way to balance a large propeller!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

The same way you balance any other propeller. Carefully, using a setup that induces as little friction as possible, allowing it to rotate on an axis that is as straight as possible.
Like this: http://www2.towerhobbies.com/cgi-bin...&I=LXHY61&P=ML
http://manuals.hobbico.com/top/topq5700-manual.pdf

Do you have a specific problem, or are you asking for directions to balance any propeller?

dow n on the dec k has a good link on doing this that is a . com site

no I did not know if it was a diffrent procedure can I use paint on the front for better vision when the prop is turning.

Absolutely! You can dip the tips into a jar of paint, or mask and spray the blades, or whatever. You just want to avoid creating a different airfoil on each blade by sanding the leading face of either blade. A coat of paint is so thin it has negligible effect.
btw, What are you calling a large propeller?

the bigest prop that I have used until now was a 12/6 I have a evolution 26gt on a gp pt19 and I am useing a 16/8 on it just wondering what the best way to balance it would be was not sure if their was something diffrent or it was the same as smaller props. just asking because this is my first gas engine.

Well, you're doing the right thing to think about it before you start hacking away, but in this instance there are no real differences. I've used the same techniques for props up to 18/10 and they work flawlessly. Keep doing what you're doing! [8D]

I like the Dubro ballancer best you can ballance any size of prop