How do you post thumbnails?

Art
1

I was wondering, how do you post thumbnails? Because I have made my thumbnail but I can’t post it. (Gimkit Creative not gimkit)

2

Click the Upload button, it looks like a picture icon

3

Ohhhh like this? Wait a minute

4

image
This Icon

6

I do this in my phone just so you know

7

oh… click the 3 dots(if there is one)