The difference between symmetric and asymetric encyption is that symmetric encyrption uses the same key for both encyption and decryption, asymmetric uses two different keys for each part.
The steps of the encryption and decryption process are that a key is generated, the key is used to encrypt a message. Then, message is put out and the reciver uses either same key or a different, private key to decode it. The reciver can then read the now decoded message.
It is important that you never share your secret key because if someone steals your key, they can read your messages, distribute malware, im personate you, etc.