You will need to export your public key and distribute it to others before anyone can encrpyt a message to you. A public key can be distributed by publishing it on a homepage, including it in an email signature, by sending it to a keyserver, or by other methods.
Export a Key
You have the option of exporting the key in an "ASCII armored" format. The ASCII armored format is a plain-text file that can be cut and pasted into email and can be read by older or buggy email clients, while the standard format provides a file that can be attached to an email message.