Right-click on the file ending in część1.rar (or part1.rar ) and select "Extract Here" or "Extract to [Folder Name]" .
The software will automatically pull data from the subsequent parts to piece the full game together. Right-click on the file ending in część1
To open a .rar file, especially a multi-part one, you need specific software: (Recommended) or 7-Zip . especially a multi-part one