Combine the blog-hosting capabilities of a site like WordPress or LiveJournal with the social aspects of Twitter, and you get Tumblr -- a service all about social blogging. If you're not familiar with these other sites, here's the rundown: Tumblr hosts blogs where members can share writing, pictures, videos and music, or as Tumblr itself describes it, "literally whatever."
Build Your Dashboard
Your home page on Tumblr, the dashboard, combines the blogs you follow into a single stream of content. Like Facebook's news feed or Twitter's timeline, the dashboard is your main stop for catching up on everything your friends have been posting. To start, just visit blogs you like and click Follow. With the exception of private blogs, there's no limitation on who you can follow -- it's not a two-way friendship, so follow any blog that catches your eye. A good place to find new blogs is on the Explore page: Click the compass icon to see popular blogs, picks from the Tumblr staff and top blogs in various categories.
Reblog and Add Your Thoughts
On Tumblr, there's no shame in copying other people's posts, as long as you give proper credit by using the reblog feature. Anywhere you come across a post you like, be it on a friend's blog page, on your dashboard or in a post from a complete stranger, look for the Reblog icon. Add your own comments, if you like, and click Reblog to add the post to your blog.
Rather than use a separate commenting system, comment threads in Tumblr take the form of reblogs. When people want to comment on a post, they reblog it, adding an additional line to the end. To read these posts, follow the indents and lines to see which user added each comment. The original source of the post is listed at the bottom. If you want to add to the comments, reblog the post and add a new line. To reblog only the original post, visit the source page and reblog from there.
Many members use Tumblr as a platform for answering questions, and the site has a built-in feature that makes it easy to send questions. Mouse over a user's profile image on your dashboard, click the person icon and choose Ask a Question. Not every blog accepts questions, but you can send a letter to anyone with the Send Fan Mail option.
Make Your Own Posts
Of course, even with all of Tumblr's ways to interact with other people, there's something to be said for sharing your own content. To add an original post to your blog, choose a type of content at the top of the dashboard -- Text, Photo and so on.
Fill out your post, whether that means writing a paragraph, clicking Upload Photo to pick an image or choosing Add Video From Web to insert a YouTube video, and click Post to send your thoughts out to the world.