I'm 19, me and 2 of my friends are going to Europe for 35 days starting on July 7th. What kind of trip should we take, what region? I want to see a lot of fun.

We can help you refine a plan, we can't create it for you . . .

Get a guidebook(s) and come back when you have at least some ideas what you want to see/do.

ricksteves.com
eurocheapo.com
backpackeurope.com

Might help you but Janis is right we need budget likes etc and a prlimanary idea of what you like. I have done this a lot backpacking when younger.My general gameplan is to fly into LON generatorhostels.com lost of acrion there. Then econoair skyscanner.net to Athens www.backpackers.gr then work my way back to LON by ferries.gr and train seat61.com hostelbookers.com party hostels Yellow in Rome is great.
www.3ducks.fr also

Happy Planning!

Also check Lets Go - written by Harvard Students, or it used to be. Fodors and Frommers are also good, but just read as much as you can.

Generally - I would recommend you fly into London - where you can more easily learn about traveling abroad - and I also love using the train in/around Europe - as it's not all that hard/long to get from one place to another.

You will be there during the busy summer season - but can stay in hostels/pensiones/B&B's, etc - but just be sure to safeguard your valuables and luggage when at the various tourist areas. In other words, keep your valuables well tucked away - and don't let your luggage out of your sight in train stations, the like.

From London - you could take the "air" boats over to the Contintent and see Amsterdam, and then work your way south to Paris, perhaps over to Switzerland - and eventually down through Italy.

I would suggest some kind of reservations for the first couple of weeks (maybve reserve for say 2 - 3 days in Amsterdam, and give a little flexibility by reserving for say 4 or 5 days in Paris - and adjust accordingly) - but also check ahead for availability where you are going. Again, it can get very busy in summer - and contacting a few places ahead of time helps give you a better idea of what will/can be available.

Of course, there are other options - but that should give you an initial overview.

Because it gets very hot that time of year, I suggest you start south and work your way north as the heat gets worse, so starting in Greece, then Italy, etc is. good idea. Of course, you could do a few days in London first and then fly to Greece, as quovadis suggests.