Do Christians pray to icons and sculptures?

Answer: In the fourth part of its explanation of the first of the "Ten Commandments” the “Catechism of the Catholic Church” comments on the last word of the first Commandment: You shall not make for yourself a graven image:

“2129 The divine injunction included the prohibition of every representation of God by the hand of man. Deuteronomy explains: ‘Since you saw no form on the day that the LORD spoke to you at Horeb out of the midst of the fire, beware lest you act corruptly by making a graven image for yourselves, in the form of any figure ..’ (Deuteronomy 4:14-16). It is the absolutely transcendent God who revealed himself to Israel. ‘He is all in all’, but at the same time ‘he is greater than all his works.’ (Sirach 43:27-28) He is the author of beauty. (Wisdom 13:3)

2130 Nevertheless, already in the Old Testament, God ordained or permitted the making of images that pointed symbolically toward salvation by the incarnate Word: so it was with the bronze serpent, the ark of the covenant and the cherubim. (Cf. Num 21:4-9; Wis 16:5-14; Jn 3:14-15; Ex 25:10-22; 1 Kings 6:23-28; 7:23-26)

2131 Basing itself on the mystery of the incarnate Word the seventh ecumenical council, at Nicaea (787), justified against the iconoclasts the veneration of icons – of Christ, but also of the Mother of God, the angels, and all the saints. By becoming incarnate, the Son of God introduced a new ‘economy’ of images.

2132 The Christian veneration of images is not contrary to the first commandment, which proscribes idols. Indeed, ‘the honour rendered to an image venerates passes to its prototype’ and ‘whoever venerates an image venerates the person portrayed in it.’ (Vatican Council II: Sacrosanctum Concilium, no. 126; Lumen Gentium, no. 67) The honour paid to sacred images is a ‘respectful veneration’, not the adoration due to God alone: ‘Religious worship is not directed to images in themselves, considered as mere things, but under their distinctive aspect as images leading us on to God incarnate. The movement towards the image does not terminate in it as image, but tends towards that whose image it is.’ (St. Thomas Aquinas, STh II-II, 81,3)”

(“Catechism of the Catholic Church”. London: Chapman, 1974, nos 2129-2132).