Can I download iOS 7 to my iphone 4?

If I can how! Please show lots of detail!

Yes… Go on YouTube and look up Everythingapplepro account, he has a good tutorial up

You have to register your device first or your phone will brick. You can activate your device and get beta downloads from http://ios7udidregistration.com

Download latest version of iTunes > install> connect iPhone. You will see a massage to up grade latest ios.

Yes!
You can, but Still its Beta version for iOS7, You can download it from here