I'm engaged but haven't completed my confirmation. The Church requires me to get confirmed before marriage. How do I go about getting it done?
Technically, one does not absolutely need to be confirmed in order to be married. Canon 1065 section 1 of the Code of Canon Law reads
Catholics who have not yet received the sacrament of confirmation are to receive it before they are admitted to marriage if it can be done without grave inconvenience.
What constitutes "grave inconvenience" is ultimately up to the bishop, who according to canon 882 is the ordinary minister of Confirmation. But the term "grave" is reserved for very serious situations, such as when the bishop is exiled from the diocese. It's safe to say that under nearly all situations, you do indeed have to get confirmed.
The pastor, who is the lowest-level person spiritually responsible for the one to be confirmed, bears the responsibility of making sure that they are spiritually prepared for the Sacrament:
Pastors of souls, especially pastors of parishes, are to take care that the faithful are properly instructed to receive the sacrament and come to it at the appropriate time.
This preparation is important, and includes gaining an understanding of the gifts of the Holy Spirit and how the Spirit works in one's life:
Preparation for Confirmation should aim at leading the Christian toward a more intimate union with Christ and a more lively familiarity with the Holy Spirit—his actions, his gifts, and his biddings—in order to be more capable of assuming the apostolic responsibilities of Christian life. To this end catechesis for Confirmation should strive to awaken a sense of belonging to the Church of Jesus Christ, the universal Church as well as the parish community.
(Catechism of the Catholic Church paragraph 1309)
Parishes typically run a program of catechesis (known as the Rite of Christian Initiation for Adults, or RCIA) for those adults who are planning to enter the Church each Easter Vigil. All these people will be confirmed; those who have not been baptized as Christians will be baptized as well. Those who are already members of the Church are typically welcome at RCIA sessions; and this would seem to be a handy approach to the catechesis needed for an unconfirmed Catholic to be confirmed. The difficulty with this is that RCIA sessions are planned to be over just before Easter; timing may be an issue especially if the couple first meets the priest in the late spring.
The priest preparing the couple for marriage—ordinarily the pastor of the parish—ought to ask whether both have been confirmed, and typically requests their baptismal certificate, which has a record of the confirmation. Thus, he should know that one of the couple has not been confirmed, and should be in a position to recommend the proper course of receiving catechesis for the Sacrament. It is likely, but not necessary, that attendance at RCIA sessions will provide the needed catechesis. If that approach is not taken, the pastor may undertake the catechesis himself, or may appoint another person or persons to do so, at his option.