Here is a tutorial for PGP key generation. The public and private key you generate can be practically used for encrypted communication with your friends.
Step 1 - Generate your public and private keys
Follow the Key generation link, press the "generate PGP keys" button and you will have you public and private keys. The field for Email Address and PGP-Key Password / Passphrase are optional. If you enter a PGP-Key password here, when you use your private key to decrypted the ciphertext, you need to provide this password.
Step 2 - Publish your public key.
Exchange your public key with the ones you want to communicate. You can also publish your public key on the webforum, so that people in the class can send encrypted message to you.
Step 3 - Encrypt your message
You can send an encrypted message to your friend with his/her public key. Follow this PGP encryption link here, enter the public key of the receiver and your message.
Step 4 - Decrypt the your message you receive
When you receive an encrypted message, you can go the PGP decryption link, enter your private key and the ciphertext you receive. If you have setup an password in step 1, you need to provide it here.
