Crrently my url is http://example.com, but I want t make it https://example.com. Please help me.
This is achieved by setting up a SSL certificate. Check with your hosting provider what options they have on offer. They might have an option for you and set it up for you. However, they might charge you a fee. There is also a great free open source solution called 'Let's Encrypt'
See also: https://en.wikipedia.org/wiki/HTTPS