How to Paint Concrete

[_Cathy_]

I need to paint our white concrete fence that has become dirty over the years.

Can someone please advise me on the specifics? I don't know what type of paint to buy and what's the best brush to use for a concrete fence. I remember our old pintor would mix liquid on the can of paint and I don't know what it is. He also has different brushes and doesn't use just one type of paint. It seems like the first layer is a different type of paint. I suppose painting is not really as simple as buying a brush and a can of paint so I need your expertise.