Ok. Do as if you are making a new post. Upload the pictures you want to use. Copy the picture's url. Then go to your post. Click edit, paste the picture url where you want the picture to be. View on preview to be sure it shows how you want it. Click update post to have it added.
You can add as many pictures as you want using this method.

You can join the PAL server on discord for more tutorial. Download the discord chat app here https://play.google.com/store/apps/details?id=com.discord

After that click the link below to join the server..
https://discordapp.com/invite/tuJsjYk

A tip while registering use same username as you use here so people would know it's you both on Discord and steemit easily

As usual this is just a suggestion. Feel free to take the one you want.

You can ask more questions if you are confused. Peace.