Custom DV SSL Implementation on Cloudflare

I need assistance with integrating my purchased Domain-validated (DV) SSL certificate with my website.

Here are the specifics:
- Server: Digital Ocean with Ubuntu
- CDN: Cloudflare
- Current SSL: Free Universal SSL by Cloudflare
- Custom SSL: Already purchased and ready for implementation
- Domain Coverage: SSL certificate to be used only for the main domain, no subdomains
We are using Digital Ocean server with Ubuntu. We are using CF and a free Universal SSL by CF. Now we want to use Custom SSL at our website.