To become one, a person has to be a Sith Warrior class and then choosing their advanced class at level 10 which can be done on the Imperial Fleet. You can then choose Sith Marauder from there.
the main sith lord in the old republic trailer is Darth Malgus
you can be jedi or sith
Darth Sidious, Darth Tyranus, and Asajj Ventress but you could argue that Asajj Ventress was not a Sith but an Assassin
to get a dual lightsaber/ double lightsaber on star wars you need to be a sith inquisitor or jedi consular and get one of these advanced classes Sith inquisitor= Sith assassin Jedi consular= Jedi shadow
Republic:- Jedi Knight Jedi Consular Smuggler Republic Trooper Empire:- Sith Warrior Sith Inquisitor Bounty Hunter Imperial Agent
Star Wars Knights of the Old Republic II - The Sith Lords - 2004 VG is rated/received certificates of: USA:T
If you mean how do you get into the Sith Enclave on Manaan then you have to go to the Republic Embassy and talk to Roland Wann, the leader. He will give you three options to choose from and all three will enable you to get into the Sith Enclave.
There is a sith in all of the star wars movies.
Play a Jedi or Sith class and finish the starting area quests.
I still can't beat him. Talk about a difficulty curve.
In Star Wars, the Great Hyperspace War was a war between the Galactic Republic and the Sith Empire. The wars started when two explorers found the planet Korriban and the Sith Empire there too. Naga Sadow remembered the vast territories of the Republic when the explorers stumbled upon their empire, and Sadow thought of this as an opertunity to go to war against the forgotton republic and conquer new territory for the Sith Empire.