Depression and self harm? How to get help?

I dont really know what to do, i've had depression for 2 years on and off...... something really bad happened and it made me relise i need help? how should i go about it im 14 and in school ino what teacher to tell but i dont know i should say? They might just think its cause of what happened and that i will be ok soon. I dont feel safe by myself i want to get away from home somewhere where i can get help?