Steemit Blockchain does not record images, only text. This is the reason you can't "host your images" in the Steem Platform. You have to upload your images to a free service and simply insert the Direct Link to your image in your post. This free service http://imgur.com (sorry, I made a typo in my previous comment) is very easy to use. You can also edit your images, resize, etc. Of course there are more free services to host images.
I recommend to read this post: https://steemit.com/steem/@billbutler/adding-images-to-your-steem-posts
I hope it helps