Cloudflare provides free basic SSL service using which you can enable https for your website.
To use cloudflare’s http service first you need to create an account on cloudflare.com
During the account setup cloudflare will give you Nameservers which you have to add in the domain settings. Every domain hosting provider whether its godaddy or namecheap has different user interfaces, you just need to find the setting to change the nameservers. Remove any existing nameserver and add the nameservers that cloudflare provides you.
You should also remove A records from your domain settings because now A records are configured in cloudflare.
Here is a video that will walk you through the process of setting up cloudflare account to enable the https service. Everything you need to setup cloudflare ssl is in this video.
This is an important plugin https://wordpress.org/plugins/cloudflare that you should install while using cloudflare on wordpress as it solves some of the issues related to using cloudflare https with wordpress.