1) If you want to upload the extracted files then please use FTP programs like Filezilla. After that connect to your server and upload the extracted files under wp-content/themes directory.
2) You can also install child theme from WordPress dashboard. To do that please navigate to Appearance > Themes and then click on Add New > Upload Theme. Next browse for the zipped child theme file you downloaded. Once WordPress has unpacked and installed the theme, just click to activate it.