I am having trouble connecting to my Wi-Fi. I have looked all around, but they are all about pi2 or model 1 or 2. When I try using the built in Wi-Fi, I enter my pre-shared key and then it says it is invalid. I have tried messing with the code of numerous files, but much to my dismay I have broken my os (Raspbian), which I have then had to reinstall. What I have found odd is that my /etc/network/interfaces is only 1 line long. Any suggestions? Remember I am running Raspbian version March 2018, Release date 2018-03-13, and Kernel version 4.9 on a raspberry pi 3 model B revision 1.2. Thanks!
It's all here, dude - a complete walk-through for setting up WiFI on your Pi - and it works for Pi3. Work through this, and come back with specific questions.
Do not make any changes to /etc/network/interfaces
Your solution is not in there. That file is completely ignored by the version of the OS that you specify.