You're really asking two questions here:
1. How to mix (safely online) with people from different cultures?
2. How do I learn different languages?
For #1 I recommend the following:
1. Epals: It's a free email system where a class (you should get your teacher to register) may find other classes around the world to correspond with.
2. TakingItGlobal: An international student run website where you may do quite a variety of things, including becoming involved in Global Project Based Learning. Again, you may find other students from around the world to communicate with.
3. Nabuur: A site where you may help a village somewhere in the world (with anything from shipping used books and textbooks to other humanitarian aid).
As for question #2:
1. Epals also has a built in language translator. As we all know, those aren't perfect, but it would be a start to learning other languages.
2. There are a number of language learning software programs. You've probably seen ads for "Rosetta Stone" but there are a number of others. I suggest you google "Computer Assisted Language Learning as well as look at the portal site I mention in sources.
I suggest you get your favorite teacher as well as your parents involved with anything you do in regards to communicating with (international) strangers. You want to keep things safe while you learn about others. There are some really bad people out there, even though the majority are quite good, and certainly learning more about people around the world is a great thing. Good luck!