There are several ways to open an existing file to be used in Gnumeric. Usually, a given file can be opened in Gnumeric if Gnumeric also allows the file to be saved in the same format. Other file formats may be imported into Gnumeric (see Section 10.3 for a list of supported formats).
The Open File Dialog can be invoked several ways. It is available in the Menubar from the File/ Open.. menuitem (see Section 3.2). There is also a toolbar Open (see Section 4.2). All these methods are equivalent.
Opening a file
File/ Open..
Open
F3
The Import File Dialog can be invoked in the Menubar from the File/ Import.. menuitem (see Section 3.2).
Importing a file
File/ Save as...