There is so much of Catholicism in the Internet now that I can provide only some of the more outstanding links:

A testimony to Catholicism's vitality in the Web is provided by these two cyber-institutions:

• The Vatican.  The seat of Catholicism itself is firmly entrenched  in cyberspace.  This is in line with its conviction that wherever man goes, the Church must be with him.
• The Catholic Webring, as the name itself implies, brings together into one network all websites that are Catholic.  Its directory is awesome!

What a Catholic believes in is handily summarized in the Catechism of the Catholic Church, multilingual copies of which exist for Internet surfers (see the link provided for the Vatican).  But hey, a complete English copy is also to be found at Misericordia!