TypeError: can't concat bytes to str, trying to use python3

问题

So the following site explains how to make an irc bot, using socket, but it only works for python2, so I tried to make it compatible, but I get the error mentioned in the title.

Here is my code:

import socket
# Some basic variables used to configure the bot        
server = "irc.freenode.net" # Server
channel = "#volafile" 
botnick = "Mybot" # Your bots nick
def ping(): # This is our first function! It will respond to server Pings.
ircsock.send(b"PONG :pingis\n")  
def sendmsg(chan , msg): # to the channel.
    ircsock.send(b"PRIVMSG "+ chan +b" :"+ msg +b"\n") 
def joinchan(chan): # This function is used to join channels.
    ircsock.send(b"JOIN "+ chan + b"\n")
def hello(): # This function responds to a user that inputs "Hello Mybot"
    ircsock.send(b"PRIVMSG "+ channel + b" :Hello!\n")

ircsock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
ircsock.connect((server, 6667)) # Here we connect to the server using the port 6667
ircsock.send(b"USER "+ botnick + b" "+ botnick + b" "+ botnick + b" :This bot is a   result of a tutoral covered on http://shellium.org/wiki.\n") # user authentication
ircsock.send(b"NICK "+ botnick + b"\n") # here we actually assign the nick to the bot

joinchan(channel) # Join the channel using the functions we previously defined

while 1: # Be careful with these! it might send you to an infinite loop
    ircmsg = ircsock.recv(2048) # receive data from the server
    ircmsg = ircmsg.strip(b'\n\r') # removing any unnecessary linebreaks.
    print(ircmsg) # Here we print what's coming from the server
    if ircmsg.find(b":Hello "+ botnick) != -1: 
       hello()

    if ircmsg.find(b"PING :") != -1: # if the server pings us then we've got to respond!
        ping()

The error message:

Traceback (most recent call last):
  File "irctest.py", line 23, in <module>
    ircsock.send(b"USER "+ botnick + b" "+ botnick + b" "+ botnick + b" :This botis a  result of a tutoral covered on http://shellium.org/wiki.\n") # user authentication
TypeError: can't concat bytes to str