Ok
Detox :
pack 4 pairs of pants or shorts / few things for wearing in bed - 5 pairs of sox , underwear. Apply this thought to shirts / hoodies.
When youget their they will take a urine test to make sure that you are indeed using opiates , and they will offer you the treatment methods - be it suboxone , methadone , or libruim with clonodine.
After a full search of you and your possessions they will take you back to your room, normally you will not have a single, up to 3 others will share it (I've been to 13 detoxes some are less per room than others).
Once they take your vitals and declare you to be in withdrawal, they will adminster your first dose of medication either right there , or at the next time on the nurses med schedule.
Likely you will meet up with a "team" be it a doctor , and therapist - or more or less - this varies - they will discuss aftercare treatment plans with you, and discuss how you will remain sober after your stay.
During the day you will have groups to attend - a lot of detoxes have NA / AA groups - some places have these manditory , some have them voluntary - I would go , the time goes quicker and you are in a place to get help and learn - these groups can offer this.
Most beds are covered in rubber so puke / urine / shit won't sink in - ask for two covers so you do not stick to the bed and wake up sweaty (sux).
Make the most of it , and it will not be too bad , hang in there

if you wanna know anything more specific just msg me, I know detoxes lol.