Setting up a Catholic website and publishing prayers is one of the kingdom of God.

Yes, creating a Catholic website and publishing prayers is considered a valid and encouraged way to contribute to the building of the Kingdom of God. The Catholic Church actively promotes the use of modern media for evangelization and spreading the Gospel. 

The Kingdom of God in Catholic Teaching

The Kingdom of God has several dimensions in Catholic understanding: 

The Reign of God in Hearts: It is God's rule in our hearts, involving obedience to His will and a transformation of one's inner life through grace and prayer.

The Church on Earth: The Church is considered the "initial budding forth" and visible manifestation of the Kingdom on earth, where Christ's spiritual reign is present.

A "Work in Progress": Building the Kingdom involves living out love for God through works of charity, teaching, and service, all motivated by the Gospel. 

The Role of Digital Media

The Vatican and Church leaders have explicitly addressed the use of social communications media, including the internet and websites, for this mission: 

A New "Areopagus": The digital world is recognized as a new "areopagus" (a primary forum for public discourse and evangelization) where the Church must be present to share the message of Christ.

A Means of Evangelization: Digital tools are seen as powerful means to reach people where they are, share Scripture, prayers, and reflections, and build communities of faith across borders.

Fulfilling the Mission: The Church would "feel guilty before the Lord" if it failed to use these media for evangelization, as they greatly contribute to the spread and support of the Kingdom of God. 

In essence, an online platform can serve as a modern pulpit and a valuable instrument for making Jesus "more known and loved, more understood and followed," which is the ultimate goal of building the Kingdom of God.