apple beta versions are not meant for the general pubic. they are typically not stable, and have half developed features.
if you are asking how to install them on a general forum like this, you probably aren't prepared to deal with problems that will pop up, just wait the month or 2 and get a finished and fairly stable product.
http://www.tuaw.com/2011/08/16/psa-this-is-why-non-developers-shouldnt-run-ios-betas/