The shops will have budtenders who can explain what you are purchasing.
With edibles, especially 1st time, take your time. I'd recommend at least 2 hrs before a second dose and find the effect builds for up to 4 hrs. Less is better until you learn how it affects you. It's important to remember you got it at a regulated point of sale and no one has ever died from weed alone if you over do it.
Watch a comedy if that happens.