Free blogging platforms (with RSS)
Twitter.com - If you currently don't have a Twitter account you should get one. It can be used initially as your blog. Later, it will server other function, but since you will evenhutally need a Twitter account, you might as well start here if you currently don't have one.
Medium - For complete newbies, I recommend this in combination with a Twitter account very highly. Get yourself a Twitter account first, and then immediately set up an assocated Medium account by identifying with your Twitter account. If your Twitter acount is @BobSmith your Medium blog URL will then be set up as medium.com/@BobSmith, and your RSS URL will automatically medium.com/feed/@BobSmith
WordPress - One of the most popular blogging platforms. Also, one of the more complex. Perhaps a good platform once you're experienced, but not the best platform to learn with.
Blogger / blogspot - owned by Google. Easier to use. Few downsides.
Tumblr - Originally bought by Yahoo, then sold to Verizon. Perhaps the easiest of all to use. A fine starter blog.