can we post pictures in our reply to a thread?

Tweet

i was wondering because just now when i was doing a post i mean i asked a question then i uploaded a picture to the thread at the same time i was replying to a friend's post, it came out the photo i uploaded in her thread instead of my thread? but when i was looking up to upload a picture to another post i was going to reply. i couldnt find the tab to upload picture.