The first time you save your work in an application, the Save As dialog asks you for a location and name for the file. When you save the file on subsequent occasions, it will be updated and you will not be asked to re-enter a location or name for the file. To save an existing file as a new file, choose File → Save As.
You can type a file name and choose a location to save from the drop-down list of bookmarks and commonly used locations.