The poem's speaker is addressing God or Jesus Christ and the two stanzas are structured to look like the wings of a bird. This is important because it creates a visual representation of resurrection and/or rising from a fall.
In the first few lines, the speaker tells God how he (God) created humans in "wealth and store," meaning he created humans with all they needed. They were created complete. In lines 2-5, the speaker alludes to Adam's and Eve's foolishness, "The Fall," and how, over time, generations became more and more "poor," falling further into sin.
In lines 5-9, the speaker asks God to allow him to rise with the resurrected Christ to sing (like a lark) how Christ overcame death. And this celebration shall inspire himself (and humankind) to overcome their fall. Again, this fall references Adam and Eve. But in this context, it is described as a Fortunate Fall because it allowed humans to know evil and sin, and thereby have a greater understanding of goodness and also have a greater understanding and appreciation of Christ's sacrifice.
In the second stanza, the poem becomes more personal. The speaker acknowledges that he was born with original sin, into a world where good and evil exist. God's discipline, through combining feelings of shame with sin, allows this speaker to see the error of his ways and allows him to better understand God's wisdom ("that I became most thinne.") The speaker then asks to join with Christ ("let me combine,/And feel this day thy victory") in celebration of his triumph over death. To join with Jesus, the speaker can "imp" his wing on God. Here, "imp" means to fix a broken wing. His wing is broken because of his sin. With God's help and guidance, his wing (sin) can be fixed (forgiven) and he can rise and fly again. And his suffering, "affliction," in life will actually advance his spiritual triumph and make it more rewarding; just as Adam's and Eve's "Fortunate Fall" advanced/made possible the eventual triumph and greater significance of Christ's resurrection.
George Herbert was a skilled poet and he stressed that his efforts in composing poetry, stylistically and thematically, were directed to demonstrate his desire to understand, love, and praise God. "Easter Wings" is a perfect example of that artistry and devotion.