How do you use the water hose thing?

So I just had the worst and most embarassing case of wall painting shit on a public toilet in Finland. Thank god your country actually cares about a clean butt and provides those shower head things on every toilet. But for the life of me I cannot figure out how to actually use it. Like to really spray your ass the water pressure is alway to low and how do you get to the butt? From the front or the back? Some advise would be great!