I'm new in python and websocket programmer.
I want to sent data that was encrypted with RSA key (in Python) through websocket to server in cloud (using nodeJs). For decrypt that data I need that key, right? 
How I can sent RSA to server and use that key to decrypt? 
Thankyou
You haven't provided information on how you are encrypting your data. But you should never send the private keys over the network. Never. Doing that is as secure as locking your house but leave the key in the keyhole. If you've done it even once, throw the key away and generate a new one.
The strength of RSA comes from the fact that anyone holding the public key can encrypt data, but only the one holding the private keys can decrypt. Think of it as an old video store's return box: any costumer can put the videos in it through the hole, but only the store staff can take the videos from it.
What you want to do is:

Generate the keys on the server 
Client call the server and grab the public key
Client encrypt data using the retrieved public key
Client send encrypted data to server.
Server decrypt it using the private key
Sent RSA Key Through Autobahn