Just starting out and I want do do backgrounds so what are good brushes to go to
Iruhas
2
I highly recommend that you try some of these brushes
and there are many more brushes you can try and hopefully you’ll find one that suits your style. 
Takiro
3
It depends on the style you’re going for. I’m more of a painter so I use the wet paint brushes a lot.
Rebecca
4
Also what sort of background you want. Abstract? Architectural scene? Landscape with organic plants?
Most of the times I use the same brushes used for the foreground, since the whole work is a coherent unit.
YRH
5
My favorite set is this one. And I usually supplement it with the basic round brushes that ship with Krita.