Hello,
First of all before the updating you would better do the backup of all your files!
If you have made changes directly in template files you will lose them after update, unfortunately.
To avoid this problem you should make your changes in child theme https://codex.wordpress.org/Child_Themes and css changes place in custom.css, in which you can override the default styling of the theme. All the CSS styles placed in this file will not be lost after upgrading the theme in the future! To create “custom.css” you can rename the file “default.custom.css” which is located in theme directory. To enable it go to Theme Options > Custom CSS > ON.
To update theme:
– Download the zipped package from ThemeForest and extract to your desktop.
– In the extracted package you will find archive blanco_theme_v2.9.1.zip, which is the wordpress theme.
– Extract blanco_theme_v2.9.1.zip file and upload the extracted folder to /wp-content/themes/ folder on your server with overwriting. You can do this via FTP.
Also before update, please, delete woocommerce folder from wp-content/themes/blanco/.
And don’t forget to backup your files!
Regards