You use everywhere to refer to a whole area or to all the places in a particular area.
Working people everywhere object to paying taxes.
各地劳动人民都反对纳税。
We went everywhere together.
我们到哪里都一起去。
You use everywhere to refer to all the places that someone goes to.
Mary Jo is still accustomed to travelling everywhere in style.
玛丽·乔仍然习惯于很派头十足地到处旅行。
You use everywhere to emphasize that you are talking about a large number of places, or all possible places.
I saw her picture everywhere.
我到处看到她的照片。
If you say that someone or something is everywhere, you mean that they are present in a place in very large numbers.
There were cartons of cigarettes everywhere.
到处都是香烟盒。