Glue for plumbing drain pipe under kitchen sink
(plumbing novice here)
What is the correct type of glue/cement/other to use when reconnecting the lower j trap-like section under the kitchen sink to the short section of pipe connected to the sink bottom?
Are there any gotchas/future considerations/other to be aware of when making this type of (minor) repair?
Also, in the (black) j trap-like section there is a removable "nut" with a white/off-white plastic ring that seems to sit within the nut.
.. is this the correct location for the ring (inside the "nut" section)?
.. what is the correct orientation for the plastic ring (seems it has a bevel/slope to it)?
.. what is the ring's purpose? (I'm assuming it may be used to help prevent any leakage at the connection, but do not know for sure)
.. what is the threaded "nut's" purpose?
Thank you in advance for any help. This forum is a great source of knowledge AND entertainment!