how can i render a picture? or where?

That's kind of a big question, but if you are just looking for where to set off a render from then 2 places
1. Under the viewport bottom far left is an icon with a cube on it.
2. In rops on the actual output node is a big old render button.

Instead of asking these questions, one per thread, I'd recommend going through the tutorials - hit the question mark on the upper right,tutorials/Quick Start. Walk first, run later.

The render button is on the lower left of the viewport - right click on that button and select “View:Mantra”. After that you can just left click to repeat.

Btw, this brings up a minor question(believe it or not) - doesn't it make more sense for the default/fresh session render button to be this, rather than flipbook? Typically a new user wants to render a piccie first, not do an animation.

Cheers,

J.C.

You are correct, it's a minor annoyance. IMO the default ought to be fast_mantra.