Reads sentences from serial port and add to string

Hi
First of all Im new in programming.
Im trying desperately to input sentences from the serial port and concat them in a string.
I know the parseInt but it does not seems to work with a bunch of letters. I searched a lot and I got void Serial.event which dont work and dont really understand.
Could you guys please help me?

Have a look at the examples in Serial Input Basics. There is also a parse example.

...R