Not sure you do
My assumption for the word docent you mean licensed guide, that can be done at the Museum and Visitor Center. There are free ranger tours for specific spots during the spring, summer, and fall. Again , information is available at the Museum and Visitor Center. Both types of tours are offered on the website as well.
call the tour center
They have a beautiful information Center, includes a movie, everyone there is so helpful
They have tour busses that leave the visitor center. Try there.
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