Paradise or Gan Eden is the place where a soul gets to once it leaves this world. There it occupies itself with the Torah based on the strengths and comprehension which it possessed in this world.
Paradise is divided into many levels depending on the level of apprehension found in each one. Basically Paradise is divided into the Lower Paradise and the Higher Paradise. Between them is the fiery river “Nahar de Nur” into which souls transitioning from the Lower Paradise to the Higher are dipped.
After that they forget the pleasures of the Lower Paradise so that they don’t interfere with their ability to receive pleasure in the Higher Paradise.
On the Sabbath, souls ascend into the Higher Paradise via a special pillar which is used again when the Sabbath departs.
The Higher Paradise is found in the world of Briya where the sefirot of Chabad (Chochma, Bina, Daat) shine, they emanate from the Torah. This place is for the righteous who served the Almighty with intellectual fear and love. The Lower Paradise is in the world of Yetzira where the sefirot of Chagas (Chesed, Gevura, Tiferet) shine as well as NHYM (Netzach, Hod, Yesod, and Malchus) within which is enclothed the intellect of Chabad emanating from the commandants.