What? Originally, all beer would have added fruit, herbs or spices. Adding fruit and spices can add complexity to the beer. Before Hops were discovered, or in countries that didn't grow hops (like Scotland), fruit and spice were used to flavour beer. There are also examples of adding pine to beer for sailors, as pine is useful for keeping away scurvy.
Where? Germany, America, Belgium, the UK. There are many places where people create fruit beer.
When? Some of the first references to beer were 7000 BC in China. This would have been a fruit and rice beer. Scotland's beer producers would have used heather or other herbs, and that beer making history probably goes back over 1 thousand years.
How? Sit in your garden on a sunny day, with a bottle of fruit beer, a glass and some friends.