how should i use in python3 to connect to Sky for Business and send some messages to user over it
The Official Skype Developer website can give you the features it supports. But unfortunately the one you need is not there.
Skype4Py should do the trick. Its not an official library. Based on the docs:
from Skype4Py import Skype
import sys
client = Skype()
client.Attach()
user = sys.argv[1]
message = ' '.join(sys.argv[2:]
client.SendMessage(user, message)
This snippet should ideally help you out.
[Update: Library compatibility with python 3.x is still a question. Alternatively you can also check Skpy which also supports python 3.x]
Hope it helped.