Answer 1

First research which encryption types there are. Current standard is AES. Look into which pseudo random number generator you can best use, you want to find one that is specifically ment for security. The default random function is not random.

Next you'll want to start implementing it. Look up some guides and tutorials. This might be one you can use: https://www.codementor.io/JUMP_LINK__&&__python__&&__JUMP_LINK/tutorial/python-encryption-message-in-python-via-reverse-cipher

Also, do not invent you're own encryption technique. Many have tried and failed. You may do so for educational purposes, but releasing it as part of a product has time and time again proven a failure. Always go for the current standards.