Welcome to CF! Glad you're here. Just click on 'Forums' in the blue navigational bar at the top and jump right in. The best way to get familiar is to browse, read, and make comments.
This is a big place, and we have various boards to accommodate almost every topic and every person Some boards are for Christians Only, some are for all. Some are for debate, while others are not (the Prayer Wall, Christian Advice and the New Christians boards, for instance, are not meant for debate).
We also have boards that are meant for specific churches/denominations/groups to gather on. As @inquiring mind said above, browse, read, and then just jump right in whenever you want to and comment If you see something that someone has written that you'd like to comment on, just hit the reply button and give them/us your thoughts.
God bless you!
--David
1 Thessalonians 5 23 May the God of peace Himself sanctify you entirely; and may your spirit and soul and body
be preserved complete, without blame at the coming of our Lord Jesus Christ.
24 Faithful is He who calls you, and He also will bring it to pass. .