IMAGE POSTING: If you want to post any image you must be at least junior member for which you will require 1 merit and 30 activity. So you need to achieve it but there is shortcut for it if you want to add images in your post which is buy copper membership.
Buy cooper membership here . But if you have achieved the junior member rank then you could follow this procedure:
Step 1: Go to image uploading site like imgbb to upload the image there
Step 2: Select the image you want to post and upload it
Step 3: Your image will be uploaded
Step 4: From the links below click on the BBC code full linked
Step 5: Copy the link and paste it on your post
[url=https://ibb.co/c3FbZB6][img]https://i.ibb.co/vqPsTF3/newbie-posting-1.jpg[/img][/url]
ILLUSTRATION :

IMAGE READJUSTMENTS: If you want to make changes like readjusting the size of your image link then you can possibly do is to adjust width and height in the link as follows:
[url=https://ibb.co/c3FbZB6][img width=400 height=300]https://i.ibb.co/vqPsTF3/newbie-posting-1.jpg[/img][/url]
I have some clarification on this one. When you want to post images, the link you use must end in an image format like .jpg, .png or . gif for the image to show. If you want to post gif there is a file size required, I think non-gif is also 2.5mb. According to this post I quoted from this
thread, the required max file size is 2.5mb.You can post whatever gif you can post as long as the file is 2.5mb or else the result will be "bitcointalk proxy. Invalid image" . For more information, open the thread. It's copper membership and not cooper membership.
OK, I increased it to 2.5.

Quoting images posted by newbies using this code
[img][/img]
will surely show the images either jpg png or gif.