In the first stanza the author tells the reader to hold a poem up to light like a color slide. This means that the reader should examine it closely, and that it may have many pleasant surprises; just like how color slides have many different colors.
In this stanza the author says, or press an ear against its hive. The hive is like a bee hive, it may look boring and inactive on the outside, but on the inside it is the opposite. This is true for poems as well. Just looking at it, the poem may seem boring, but after reading and analyzing it the poem becomes very interesting
The stanza tells the reader to put a mouse in the poem and watch it probe its way out. This means that poems can be challenging like a maze, but can also be enjoyable.
In this stanza the author tells the reader to walk into the room and feel for a light switch. Just like how when you are in a dark room the light bulb will light up the room, the poem's light switch might help one understand the poem more.
This stanza says to water-ski across the surface of a poem waving at the author's name on the shore. What it means is that water skiing might be hard at first, but once you know how to do it, it is fun. Just like how at first poetry is hard, but as you get more comfortable with it, it becomes fun to do.
The last two stanzas state that people tie the poem to a chair and beat a confession out of it to find what it means. One can infer that the author thinks people treat the poem like a criminal, yelling and poking at it until they get an answer.