Replying To A Formal Invitation

Centered on the page, without the dashes or bracketed editorial notes:

-[Your Name]
-accepts with pleasure
-the kind invitation of
-[The people inviting, exactly as worded on the invitation]
-for
-[The day, and date as worded on the invitation]
-at [the hour, as worded on the invitation]
-[The address, as worded on the invitation in as many lines as accorded it on the invitation]

The address is generally omitted these days, so you may do so with impunity. If the ceremony is in a house of worship, you technically reply for the reception (with the reception time and address) because no one can invite or exclude people from a house of God, but this often causes confusion these days among the unchurched so it helps to know how educated your hosts are on such fine points of etiquette.