There are 2 options of how to update your theme.
Option 1 (automatic):
Install recommended Envato Market plugin. Generate an Envato API Personal Token, paste the token and save changes. When the theme has new update, you will see the notification and can update it on the fly. Read more about how this process works at envato.com
Option 2 (manual, using FTP):
- Extract the theme package that you downloaded from Themeforest and unzip the estand.zip file.
- Connect to your server via FTP and navigate to /WP-CONTENT/THEMES folder of your WordPress installation, replace the existing folder named estand with the unzipped folder.