Make a directory named /webgrabber-wordpress-plugin under the /wp-content/plugins directory.
Copy entire archive contens to the new created /wp-content/plugins/webgrabber-wordpress-plugin folder.
Activate the plugin through the 'Plugins' menu in WordPress administration page.
Use [webgrab] short code into posts/pages editor, or drag and configure a widget under the 'Appearance/Widgets' section.
If you want to embed various contents from public web sites into your WordPress blog, then the Web Grabber WordPress Plugin is the perfect tool that will help you do that.
No frames or iframes involved! Real HTML content, grabbed form the web and displayed in whithin your blog just like you wrote it by yourself.