The first calling down of the Holy Spirit is over the bread and wine that will immediately, through the consecration become the body and blood of Christ.
The second calling down of the Holy Spirt is over the congregation, the people of God.
Sad, sad, sad...You don't call down the Holy Spirit...No one can call down the Holy Spirit...
If this is Catholic teaching, it is just astounding how the ignorance about Christianity pervades the Catholic religion...
Have you received the Sacrament of Holy Orders and have the additional graces to do this?
Priest have received the Sacrament and do have the additional graces.