You can do your blogging by typing into a web browser form provided by the Movable Type service. But boy is that clumsy and awful.
So for a while now I've used so-called "blogging clients" which provide a nice rich interface to write and edit the posts, and then use the server's APIs to actually send the update or change up to the server.
On Mac, I use the fairly wonderful Ecto for OS X - Recommended!
On Windows, I tried all the free ones that I found recommended, and only w.bloggar was stable enough to actually use, although I didn't like the user interface. I also tried tried ShartMT and Ecto for Windows.
Despite my best efforts, neither one was stable enough to use. In the end, I found and am now using the BlogJet - Clean and simple.