To perform upload/download the object in the object storage, you can either use API, or client software.

【Object storage administration by API】

You can directly execute the operation of the object storage by using cURL or the like. For API commands, refer to this link.
For information on API commands, refer to this link.

【Object storage administration by client software】
You can execute the operation of the object storage by using client software available for public,
For client software, you can use CLI based Python-swiftclient, GUI based Cyberduck, or the like.