www.stumbleupon.com/downloads
Hi, If you click on the StumbleUpon link I've added here, then literally just drag the 'link' of the Stumble Upon toolbar up to your toolbar, then the 'Stumbe', 'Like it' and 'Thumbs down' appear on your toolbar.
You don't need to register your blog with stumbleupon, instead you click the thumbs up when you are on your blog page. It then gives you the option to simply add the site without adding anything further, or to give it a brief review and allocated particular tags to it (i.e. you can tell SU more about the page by putting it in the right categories.) Once you done this, the page you've thumbed up automatically is added to the Stumble Upon database and will become on of the sites that others are presented with when they 'stumble' themselves to find sites.
Nickie at I Am Typecast did the original post that I followed: Find that here:
www.iamtypecast.com/2011/12/what-is-stumbleupon.html
As for Technorati. You can join it without necessarily claiming your blog, which won't do anything for your ratings, you'll just be a member without them necessarily being away of your blog. You have to go to your profile page in Technorati and at the bottom you have the option to 'claim' your blog. It involves adding a unique code to one of your blog posts so they can trawl the internet and confirm that you are indeed the author of the blog. Once done, your blog is added to their blog roll. It is then allocated a Technorati Authority score which is based on how many other sites linked to yours among other things. In general people add their blogs here as you need a technorati score to creep up the Tots100 ranking charts for example. Higher rankings, better scores equal move visitors.
I don't think, on it's own, it'll drive much traffic.
To be honest my traffic has increased pretty quickly since I joined and started regularly using Twitter. That's my best traffic source now. @ymummyreally if you are interested
Hope that all helps!!
have fun