Website authority used to be visible by your page rank, you know, the green bar giving you a page rank of between 0 and 10, with 10 being the ultimate goal.
One of our websites made it to a page rank of 6 which was quite an achievement.
The thing was though, people spent way too much time on page rank and thinking without a high page rank they would never make any sales, this really was not the case, many low ranked websites made a lot of money.
Googles Matt Cutts suggested he would be surprised if there was any page rank updates this year but it seems Google has already just done exactly that.
The thing is with page rank now, it will soon be discontinued so just try to get on with promoting your website using the traditional backlinking, blogging, social networking and keeping your site up to date as much as you can.
You can check your page rank here; prchecker