icon is not working

[process_steps]
i got this code by demo live page.

and i add at one of my page. it’s working. but the each of icon is not shew up.
can you give me a guide to fix it?

http://bkinckorea.com/?page_id=54 here is my page link.
thanks.

[process_step title=”Idea” icon=”icon-lightbulb”]Sed bibendum quam sem, sit amet interdum justo fringilla id. Praesent adipiscing ac tortor vitae sum.[/process_step]

[process_step title=”Design” icon=”icon-star-half-full”]Sed bibendum quam sem, sit amet interdum justo fringilla id. Praesent adipiscing ac tortor vitae sumt.[/process_step]

[process_step title=”Development” icon=”icon-wrench”]Sed bibendum quam sem, sit amet interdum justo fringilla id. Praesent adipiscing ac tortor vitae sum.[/process_step]

[process_step title=”Deployment” icon=”icon-rocket”]
Sed bibendum quam sem, sit amet interdum justo fringilla id. Praesent adipiscing ac tortor vitae sum.
[/process_step]

[/process_steps]