i enjoy picking fruit.  fruit picking is a season activity that occurs during the harvest time in areas with fruit growing wild or being farmed in orchards
What is considered harvest time?  Is it just a set time every year?
it really just depends on the type of fruit you are picking.  they also have harvest festivals that are annual celebrations that occur around the time of the main harvest of that region
That is neat.  So what types of fruits are picked?  
Apple picking is a big fruit in the US.  Apple orchards are even open to the public in some areas that allow customers to pick their own apples or they can also purchase pre-picked apples
Are there certain parts of the US that are especially known for their apple orchards?
Yes, apple picking is very popular in the midwest of the united states of america
Is that also were apple cider comes from?   I really enjoyed drinking that as a kid.
Apple cider
Apple cider (also called sweet cider or soft cider or simply cider) is the name used in the United States and parts of Canada for an unfiltered, unsweetened, non-alcoholic beverage made from apples. Though typically referred to simply as "cider" in those areas, it is not to be confused with the alcoholic beverage known as cider in other places, which is called "hard cider" in the US and Canada. 
It is the liquid extracted from an apple and all its components,
Fruit picking
Fruit picking or fruit harvesting is 
a seasonal activity (paid or recreational) that occurs during harvest time in areas with fruit growing wild or being farmed in orchards.
Types of fruit.
Types of fruit Apple picking.
Sultan kamara
Apple picking is an activity found at apple farms. Apple orchards may be opened to the public, allowing consumers to pick their own apples or purchase pre-picked apples.
Although this is ultimately a method of purchasing apples, it is often a social activity