Here is a guide on how to post an instructable via iOS.
Step 1: Download
Download the Instructables application via the App Store.
Step 2: Create
Create an account, or log in with Facebook.
Step 3: Open the Menu
Open the menu at the top right of your screen and click "New Instructable"
Step 4: Select
Select your category and language.
Step 5: Add
Add images and text as you see fit.
Step 6: Click
Click "Publish" at the top right of your screen. Also, add "Tags" or words that relate to your post. If you are doing a piece on making eggs your tags may include "Breakfast","Bacon", and "skillet". Once you are finished, click publish at the bottom of your screen and you are done!