What are Gohenom and Gan Eden? Is it common to go to Gohenom before Gan Eden?
Gehinom is usually meant in Hazal to be what Yirmiyahu said, I just want to add that occasionally Hazal will speak about an extremely infamous and wicked person who is "there" forever. "Gan Eden" is used to refer to the "place" in the spiritual dimension that one either goes to after Gehinom to enjoy "proximity" with Hashem, or if one is exceptionally righteous, goes directly there to enjoy and wait. When the revival of the dead happens those people will come back to this world from Gan Eden. I will not explain the famous mahlokes about the meaning of the term "Olam Habah" because that was not the question. I'll just point out that this "Gan Eden" which you are asking about seems to be what Rambam would appear to call "Olam Habah."
I don't have any sources at the moment but the general impression is that Gehenom is not punishment per se, but the difficult process of the neshama divesting itself of the gashmius/physicality it indulged in in a prohibited manner throughout life and being cleansed for transgressions which one did not do proper teshuvah (repentance) for. Only the most worthy individuals will not need this process. Nevertheless when the process is completed the neshama will receive it's share in the world to come (Olam Haba/Gan Eden) provided one did not commit a sin which is punishable by Kares (being "cut off" from Am Yisrael and Hakadosh Baruch Hu) without proper repentance.
(Medrash Rabbeinu Bachya, end of Aharei Mos; Ramban, Shaar HaG'mul)