how can i save a document by chosing where I want to put it (in the usb-key, for instance)

i used windows until now, there I always could chose where I wanted to save a document
here I read only "save" and i even have trouble to find it again if i did not save it as a word or excel document

I do not know how to create folders and to handle them as easily as in windows....
I thought that linux is easier to handle....

thank you
andrea hanke