Big Games are splip in smaller parts and compress into a file! Some files are compress with Winrar, programs can extract mayn formant such as: .rar/.7/.001/.002/...etc - provided they are updated to the latest version.
2. Install latest WinRAR or 7-Zip, this is important! old Winrar can't extract new packages.
3. Then right click the game and click "Extract to Name of game".
4. Then right click trhe first part only and click "Extract to name of parts". That will extract the whole package. You don't need to do anything with the other parts.