If you have configured the program's associations with files, then you can open the file by double-clicking it from Explorer or another file manager. How to set up associations - see Settings

You can also open an exchange file using the Open command (menu File→Open... ) or Compare (menu File→Compare... ). The difference between these commands is that the open command closes all other exchange files opened in the program. The compare command adds one more file to the list of files opened in the program.

The file opens in a tab with its name. Automatically, after opening the file, the format is determined and the contents of the file are reparsed in accordance with a certain format. All parsing errors and warnings for this exchange file are shown in the message list.
After successfully opening the file, the drawing tab will be shown. On it you can see the boundaries of objects (parcels, lands, zones... ) contained in the file