Here is a Blessing you may include in your ceremony.

Celtic Wedding Blessing

May your mornings bring joy and your evenings bring peace. 
May your troubles grow few as your blessings increase. 
Be no worse than the happiest day of your past. 
May your hands be forever clasped in friendship 
And your hearts joined forever in love. 
Your lives are very special, 
God has touched you in many ways. 
May his blessings rest upon you 
and fill all your coming days.