Can I take content from the internet because it is a public domain? How?

NO - the internet is NOT public domain. Content posted on the Internet is owned by the person who made the content - even if the owner did not post it. There are materials on the Internet that have a free license for reuse - but this is not true for all content. Do not copy unless you know the material is free to be copied.

The internet is not "public domain." Public domain includes only those works that no longer fall under copyright protection. You can generally assume in the U.S. that anything that was published or otherwise released to the public prior to the late 1920's is in the public domain. It doesn't make any difference if you download the works for personal use or for international distribution; it's still theft because you don't have permission to do that. It is generally assumed that persons who place works on the Internet will not object to another's use of the work without permission. But the copyright protection still exists and owners can and do track down illegal downloads. Furthermore, much of the material on the Internet was placed there illegally without permission from the copyright owner.

It is not true. You may be able to do what you are talking about due to fair use, but things on the internet are definitely not automatically in the public domain. Search for info on Fair Use and you may get what you need.