For me Facebook is to keep up with my family and friends, many of whom are scattered all over the world. You can, however, also start a Fb page which is for announcements of new books or shorter stories which have been published, links to reviews of your books, etc. You might also want to post on your Fb author page links to stories about interesting events in the publishing world, and so on.
A Fb page for your author persona, however, cannot be as rich and flexible as a blog. Other threads in this forum have discussed free and paid platforms, so I suggest you look into those. Personally I prefer WordPress.com which is very easy to set up. It takes literally a minute or two. But as time goes by you can add all sorts of capabilities not available in Blogger and so on.
Your blog should reflect who you are as an author and the kind of works you have created and want to create, your unique public self. Beyond that, following is the advice professionals give to those new to the world of web sites.
START SMALL, STAY SMALL as you can. TAKE BABY STEPS to adding stuff to your site. Try to MAKE IT EASY FOR VIEWERS to get around in your site. KEEP YOUR POSTS SHORT. Or put long ones in the "static" (rarely changing) part of your site, and put a short intro to the long post in the "blog" (changeable daily) part of your site.
