I start from the assumption that you have a functioning Zope/Plone instance and that you have correctly 'installed' the QuillsEnabled code.  The easiest way to do this is with buildout and including the Products.QuillsEnabled egg.

Now, go to your Plone instance, navigate to the portal_quickinstaller, and then install Products.QuillsEnabled.  This should lead to both Products.QuillsEnabled and quills.app appearing in your list of installed products/packages.

Next, create or navigate to a folder that you wish to act as a weblog.  Click on the 'Actions' drop-down menu and select 'Activate blog'.  You should now see that the folder has been 'decorated' with various blog-ish features.  Most notably, it should have a selection of new portlets such as: a 'tag cloug', 'recent entries', syndication, 'authors', and a 'weblog admin' portlet.

Great, you're basically there :).

To start actually blogging, just add a 'Page' (or 'News Item', if you prefer the features offered by that) type to the folder.  Once you're done editing your new Page-ish content, 'publish' it (in the standard Plone workflow sense) and then go back to the weblog-ish folder that you first created.

You should now see your newly-published post in the weblog view.  Some of the portlets should also have a little content now to reflect your new post - i.e. 'recent entries', 'authors', and 'weblog archive'.  If you added 'categories' (in the standard Plone keyword-ish way) to your post, then the tag cloud will also reflect this and provide you with links to listings of all posts in the weblog that have each of those 'tags'.  These are referred to as 'topics' in Quills.

People can actually subscribe to syndication feeds (i.e. RSS and Atom) for either the entire weblog or for each of the individual 'topics'.  'Neat', I hear you say ;-).

Actually, there is equivalent functionality for each individual 'author' who has posted to the weblog.  A listing of all posts made my each author is available, together with syndication feeds for them.  'Double neat', I hear you say ;-).

QuillsEnabled comes with a fair number of configuration options that are available via the 'Weblog Admin' portlet.  Click on 'Configure Blog' to access these.  You'll find you can adjust how much of each post gets shown in the weblog view (i.e. just the excerpt, if you wish).  You can configure which workflow states QuillsEnabled should consider as being 'published' and which to consider as being 'draft' - which makes it easy for you to use QuillsEnabled with your own custom workflow.  Other options are available but I'll let you find them yourself.

Finally, if you decide that you want to use some kind of remote blogging tool - like ScribeFire or Ecto - you can enable this as well.  Go back to portal_quickinstaller and install QuillsEnabledRemoteBlogging. Note, though, that you will have to have included this in your zope installation/buildout for it to be available.  It is an optional extra for QuillsEnabled.  The QI tool install process should also install MetaWeblogPASPlugin.  With that done, you should now have MetaWeblog API support for all your QuillsEnabled-enabled blogs.