Open a spreadsheet stored somewhere other than your Mac (such as iCloud Drive): In Numbers, choose File > Open (from the file menu at the top of your screen). Numbers shows up to the last ten spreadsheets you opened.
Open a spreadsheet you recently worked on: In Numbers, choose File > Open Recent (from the File menu at the top of your screen). For an Excel spreadsheet, drag it to the Numbers icon (double-clicking the file opens Excel if you have that app). Open a spreadsheet on a Mac: For a Numbers spreadsheet, double-click the spreadsheet name or thumbnail or drag it to the Numbers icon in the Dock or in the Applications folder.