I'm just curious about what happened after Sauron was defeated for the third or fourth ( I forgot ) time .I've read a few things but they didn't say much except after the death of Aragorn II Legolas and Gimli sailed to the Gray Havens. Are there any stories about the 4th age and what are the books containing these stories called.

there's a single story set in the 4th age, which you'll find in the HoME book 12: Peoples of Middle-Earth.

aside from that, read the "letters of JRR Tolkien".

only those references I can think of.

Suz.

Gandalf says: "my journey is over and now its the time of the king" or something like that <-- LOTR 3 for Playstatio 2 when you completed the game

But Sauron wasnt evil it self, thats Melkor(Morgoth) so it must be up to the reader to think futher on in history..

Sauron is no more. When the ring was destroyed, his power was reduced so greatly after his defeat that he would never recover from it and thus remain 'a spirit of malice, forever gnawing at itself' or something like that. So, Sauron's time is over; he was the last physical manifestation of Evil on Middle-Earth, and the next time a Dark Lord will arise won't be until the Dagor Dagorlath, a battle similar to Ragnarok, and that Dark Lord will of course be Morgoth.