Why am I unable to private message someone on IRC?

[jwnasambu (Juliet Wamalwa)]

I have failed to hold a direct conversation with any person on IRC. When I sent the message this is what i get

You must log in with services to message this user.

What could be the cause and its solution?

[reubenv (Reuben Varghese)]

@jwnasambu , which IRC client do you use?

[jwnasambu (Juliet Wamalwa)]

Am using HexChat.

[ivange94 (Ivange Larry Ndumbe)]

when you say message someone do you mean like sending a private message or mentioning the users name in the public channel?

[jwnasambu (Juliet Wamalwa)]

I mean sending a private message.

[burke (Burke Mamlin)]

The user you are trying to message has blocked unidentified private messages. To reach them privately, you must first identify yourself on freenode by registering your nickname.