SOS with uploading

Sorry, but that doesn't ring a bell, can you please explain. As you can see I'm new and a newbie. How do I see what my bootloader is? I think I just downloaded a bootloader a while ago.

Are you using a board with a 57600 baud bootloader?

Is it bad or something?
Edit 1: I asked my dad and he said it should be 9600.
I tried this simple code

void setup() {
  Serial.begin(9600);
}

void loop() {
  Serial.println("hello world");

}

but it didn't work, it still showed that error.