All you need is an internet connection and a strong desire to know what has been going for the last 100 years or so. If you want learn about ETs who were here thousands of years ago, check out Ancient Aliens.
The modern age for UFOs began at the end of the 19th century with a crash in Aurora Texas. This was well documented because there weren't any government agents around to create disinformation.
Another way of contacting ETs is through channeling which leads to contacting aliens directly or gaining secret information on alien cultures. George Van Tassel in the 1950s was a prime example of an ET psychic. Some might consider him six parts science fiction and six parts new age religion.
There's even a documentary on the airforce base (Wright/Patterson) where crashed UFOs and alien bodies were sent in the 50s, 60s, and 70s.
If you'd like an overview of the UFO coverup over the last 70 years, check out "The Washington Disclosure Hearings In 2013".
There is more material on UFOs than this, but I've tried to select information that would be the most real to the average person on the street.