Very simple!  Once you've created your free account, you will have your own personal home folder.  To get to your home folder, choose "my folder" from the orange bar at the top right of every page.  Since you are the "owner" of that folder, you will see a green border around the main content area.  In the upper right of that green border will be an "Add Item" dropdown menu.  Choose "weblog" from that menu and you're on your way!

Also, Allô! has the idea of a "workflow" for each item.  In order for others to see your blog, you must 'publish' it.  Once you're done creating your blog (or any blog entry), you'll see a 'change state' dropdown menu in the green bar.  Choose 'publish' from that menu, and you're done! 

Don't forget to publish news items, events, or blogs.  This will make sure they show up in the various areas of the site.

A workflow allows you to see your item and make changes before publishing it for everyone to see.  If you ever want to take an item down, simply use the 'retract' option.  You can also make things private by using the 'make private' option.  But at first, all you need to remember, is to  publish your items.

~Tom