With a title like "A Birthday," you're probably expecting a setting like a pool party, or maybe a Chuck E. Cheese. Well, we hate to disappoint you, but there are no ball pits or video games in this poem. And a five-foot tall animatronic mouse is really out of the question.
In fact, there's really no actual physical setting to this poem at all. It's entirely internal, taking place against the backdrop of the speaker's emotional reality. You could guess that much probably by the third time you read "My heart is like…" That anaphora in the first stanza is a constant reminder that we're dealing with the speaker's inner world.
Of course, things start to take on a bit more physicality in stanza 2, when the speaker starts drafting the blueprint for the best dais ever. Is she really asking for a literal platform to be built, though? It's doubtful, particularly given all the Christian symbolism going on in stanza 2.
Nope, the dais is better understood as a figurative setting, upon which the speaker's "love" (a.k.a. God) might find a place worth taking a load off. That's got to be one fancy piece of furniture, which is why the speaker is so demanding in her decorating instructions.