That file name, september_7th.part1.rar , indicates it is [1]. To open it, you will need the rest of the parts (e.g., september_7th.part2.rar , part3 , etc.) located in the same folder [1].
If you can, I can help you find the specific extraction password or troubleshoot a download error. september_7th.part1.rar
Select "Extract Here" or "Extract to..." using your software [1]. That file name, september_7th