How can I get one of those pictures??

Use mobile, that way you don't have to see them.

That file size it too large, gonna have to resize.

Go into your settings by clicking the settings button and you will see a text box called "Signature Image" near the bottom of the page. When you find a picture you like you need to right click it with your mouse and select "copy image URL" or something similar. Once you have copied it you need to paste it into the "Signature Image" text box. Then you just need to hit the "submit" button at the bottom of your settings page and you will be good to go! LMK if you have any questions, its pretty easy.