To move your current blog to an OverBlog, it only takes a few clicks.
Once you have created your account, go to Settings > Import/Export. Type your current blog’s URL and select the platform. At this time, we support imports from Blogger (Blogspot), Dotclear, LiveJournal, Tumblr, Wordpress, Posterous and Typepad.
Each platform has its own process, you need to follow them carefully.
for Wordpress, you need to send your archive
for Blogger, you need to give your authorization
To import a blog on OverBlog, you have to be the blog owner.