I haven't figured out how to embed the picture straight from the mobile app... but from the laptop / computer:
Sign on to your Flickr account (no kidding...lol)
Go to your uploaded photos in your camera roll & select the pic you want
Lower right there is an arrow that allows you to share the pic
This takes you to a screen where you can select the size of the photo you'd like to embed...
Right click and copy - then paste it into the reply window here
Here's a youtube video of similar:
https://www.youtube.com/watch?v=qjy6-u6RU3gI'll be anxious to see if there's any other tips from members here. I do know that PhotoBucket is a pain in the rear-end now!