When i try to make a shop for my head textures, it seems I can never paste a picture into the thread i can only attach it or put a link to it on a website but i can just paste it because it says i have like 500,000 characters. How do i paste pictures on a forum thread?

You don't paste them, you upload the image to somewhere else & use the [img] tags

For example tinypic.com

Upload your desired image and then use the tags

[IMG]tinypic.com/d3tn5id[/IMG] <-- This would be the actual image (But I used noparse for an example)