Facebook is a public software.

Hello Rosie! This is an interesting composition. Thank you for sharing your thoughts about Facebook. You did an excellent job! Keep it up!

Facebook is very useful to exchange messages with familiar persons.

>>Correct

 >>Or

  >>Facebook is very useful for exchanging messages with other people.
Facebook have a very private information I think.

>>Facebook has very private information I think.

 >>Or

  >>I think, Facebook has a piece of very private information.
 It can connect me to the world.

>>Correct

 >>Or

  >>It allows me to connect to the world.
 Thanks to Facebook, I can read and write messages.

>>Correct
I love Facebook.

>>Correct