hi, ok, 2 quick things.

1. to add pictures to your post, just click on Editor, you'll see little drop down menu, looks like Wordpress, if you're familiar. There is a little image icon (to the left of the 'normal' box). Click on that image icon. A little rectangular box appears. There you will add the URL for your photo. What is that you say? Well, that brings us to the next thing.
2. You need to upload all your photos to a photo sharing site before you can add them to your Steemit post. Try imgsafe.org, it's brilliant and easy. And this applies to your iPhone as well. Exact same thing. So...
   Whether from your computer or your phone, or whatever... you upload your photo to your, let's say, imgsafe account. When you open your photo on that site, you get the URL of the photo. That is the URL you will use, when you're posting to Steemit and that little rectangular box comes up, and you need to have a URL to enter. Well, that is your URL, that is your box, copy and paste your URL into this box, and click the little check mark. Your photo will go into your post wherever your cursor is at the time. And yes, you need to do this for each photo you want to use. Here's a secret tip just for you - imgsafe will allow you to upload more than one photo at a time. Just select how ever many photos when prompted. If you do this stuff a lot, you will find this feature an incredible time and headache saver.
   Happy posting. Cheers to all.