how can i create a repeating backround of a specific symbol / logo ?

[datfknadam]

just like here http://prntscr.com/d6mpyh

for example, I'm creating a shape layer with a circle, do people really copy and paste the layer and position them correctly? or is there any specific effect for that?

[Mylenium]

That halftone pattern in your screenshot would probably be most easy to create using third-party plug-ins or the respective filter in Photoshop. It can also be created using stock AE effects like Motion tile, CC RepeTile and Card Dance to create an array of circles and then scale it based on a gradient map. Nothing too complicated, but obviously it will require some basic knowledge of how these effects work. Likewise, shape layer repeaters could probably be used to some extent. Realyl depends. For other patterns other techniques may apply. There isn't a "one fits all" solution and yes, on complex patterns it can mean that you end up placing a lot of layers manually.

Mylenium