Help on how can you post a picture in your signature block and whats the limit of picture size in profile pic.
You add an image to your signature the same way you would put one in your post.
yourimage.png
You can also embed links into the image like my yoyonews one for example.
[url=http://yoyonews.jp/]http://i.imgur.com/1UHszgJ.gif[/url]
For avatar sizes the max is 200x200 pixels. Though I suggest not making it any wider than 130 or else you’ll have a scroll bar and you can’t view the whole image at once.
It varies depending on your screen size and the page zoom.