How do you insert 'share this' (for Twitter etc) buttons on a wordpress blog/website?

If your blog is hosted at Wordpress.com you will not be able to use plugins to achieve your goal. See their post here:

http://en.support.wordpress.com/plugins/

You'll need to manually paste the html for Tweet This, or Digg This to each post you write.

However if you are hosting the Wordpress Blog on your own server you can upload any number of Web 2.0 Sharing plugins to the /wp-content/plugins directory.

I would recommend getting "Social Bookmarking Reloaded" it supports all of the following sites:

Del.icio.us, digg, FURL, blinklist, Socializer, reddit, Feed Me Links!, Technorati, Newsvine, Ma.gnolia, Google Bookmarks, GOOGLE BUZZ, Squidoo, BlinkBits, Stumble Upon, Netvouz, Rojo, Blogmarks, Co.mments, Scuttle, Tailrank, Bloglines, Segnalo, OkNotizie, Netscape, Bookmark.it, Ask, linkagogo, del.irio.us, Socialdust, Live MSN, Slashdot, Sphinn, Diggita, FaceBook, Upnews, Wikio, HealthRanker, Barrapunto, Notizieflash, Kipapa, Fai informazione, Blogmemes, Blogsphere news, Blogsvine, Mixx, Scoopeo, Myspace, ZicZac, Twitter, IndianPad, Technotizie, Blue Dot, Connotea, Diggitsport, Tipd, forexassessment, FriendFeed, digo, buzz

(Notice Twitter IS in the list)

You can read about it and download the plugin here:

http://wordpress.org/extend/plugins/social-bookmar...

Or, if you use your Wordpress Admin area to install plugins (Click Plugins -> Add New) you can search by the keyword:

Social Bookmarking RELOADED

Look through http://wordpress.org/extend/plugins/search.php?q=t... or do a web search for wordpress twitter button

I found a free download of WordPress here http://j.mp/1yyn49q

Wordpress is probably the most elegant and professional blogging platform