If you need ssl certificate and you want to know how to order ssl you can follow this post.
First you should know which type of ssl you need .
there is some ssl types like DV, OV, or EV.
you can follow ssl types and differents in the link below.
SSL Types and differents
when you have choosed ssl type you can choose ssl brand like geotrust comodo or verisign.
Then you can order like this.
To Order SSL, Click Link Below.