This is actually from Act II, scene iii.  This scene directly follows the balcony scene in which Romeo and Juliet confess their love to one another and Juliet tells Romeo that if he is serious about their love he will marry her.  In Act II, scene iii, Romeo goes to Friar Lawrence's cell to ask him to marry them.  This is what Romeo begins to ask in lines 60 -61 when he states,

     "As mine on hers, so hers is set on mine,
      And all combin'd, save what thou must combine
      By holy marriage. When, and where, and how..."  (A.II, s. iii, lines 60-62)

The following lines are actually where Romeo asks the Friar to perform the ceremony when he says,

     "I'll tell thee as we pass; but this I pray,
      That thou consent to marry us to-day,"  (lines 64-65)