I've built a transmitter similar to this one. I want to use it to make a small "radio set", which would only consist out of a button for sending morse code and a LED to see what someone else is sending. How can i build a Receiver for this kind of transmitter with as little parts as possible? I would really appreciate your help and im really sorry if i spelled something wrong.
Greetings from Germany! 
You want 800 MHz or 800 kHz?
For 800 kHz AM the least number of components you need is 5: inductor, variable capacitor, diode (germanium type), fixed capacitor, headphones. Commonly known as crystal radio.
Have a look at the Moteino web site - they do the Rfm69 board on a custom Arduino.
Don't do it!
Laß die Finger weg, wenn Du nicht Besuch und Rechnungen von der Post oder noch übleren Zeitgenossen bekommen möchtest. So ein Sender funkt noch bis weit in den MHz Bereich hinein, das gibt Ärger!
Greetings from Germany