How to Upload Downloaded .Zip Files to WordPress

Themes
1. Log in to your WordPress installation's dashboard.
2. Click the 'Themes' link under 'Appearance' in the left sidebar.

3. Move to the 'Install Themes' tab.
4. Select 'Upload' from the list of options at the top of the page.
5. Click the 'Choose File' button and select your theme's ZIP file, then click 'Install Now.' This automatically extracts your theme from its ZIP file and installs it in WordPress.
Plugins
6. Sign in to your WordPress installation.
7. Click the 'Add New' link under 'Plugins' on the left side of the screen.
8. Select the 'Upload' option from the top of the page.
9. Click 'Choose File' and open your plugin ZIP file, then click the 'Install Now' button to automatically install the plugin.