With your current rank Follow these Steps:
Step 1: Buy a Copper membership here: https://bitcointalksearch.org/topic/how-to-add-photos-to-a-post-5479714 (Price is around 0.00065789 BTC)
Step 2: Upload Image to TalkImg: https://talkimg.com/
Step 3: Copy BBC Embed Code (Look like this: )
Step 4: Paste the Code in your Post.
After doing these 4 steps your image will be visible in your thread/post.
If you want to Skip First Stop. and don't want to buy a Copper membership. then you'll have to rank up your account to at least JR member rank. to be able to add images in your post.