Light them in front of the crucifix and/or icon in front of which you pray. Or if you have like a small home altar.
Then pray in front of them.
The light and the fire also symbolizes God because He showed Himself like a fire in front of Moses. It also symbolizes our burning hearts in adoration of God.
May God bless your prayers in front of your candles.
I found this small prayer to be said as you light your candle up:
Most Holy and High Trinity, receive my love before Thee and burn with Your Godly fire my iniquities and erase all my mistakes, O, Lord, give them to your forgiveness and burial. Amen.
Most Holy Mother of God, make the light of my gift be well received by your Son and our God, for the forgiveness of our sins. Amen.
Don’t put it out. Let it burn until it’s consumed.