I cant' attach pictures on a post

I want to attach some screenshots of my phone's wakelocks and alarms to a thread. Whenever I attempt to choose the "insert image" icon, I only get the option to copy a link of the photo I want to post. I wan't to be able to attach the photo from my phone, or computer so that it shows up in my post.
I do get the option on the xda app, but whenever I choose the photo, the only option I get is to cancel the attachment.
Please help me with this, I really want to be able to attach my pics.
Thanks in advance.