How do i make free calls from my pc in korea

You need to re-post your question in a more readable form.

You have 3 totally unrelated questions. Calling using a "card" which you don't say what card. If it's a calling card, from who? I don't think you can or even need to use one if using a computer call as in Skype or a similar service.

Calling from a laptop.

And calling from a phone booth.

Need more details.