The first place you should blog is on your own website or personal blog on a blogging platform as I outline in my book. Get some experience writing about your learning process and try writing some articles or tutorials. You should only apply to guest blog once you have some practice as well as some high quality content to draw people into on your own blog.
I recommend the following sites for guest blogging:
Comment below if you have any more guest blogging suggestions or questions about blogging.