Use PuTTY behind a Proxy

I would like to use PuTTY behind a Proxy, but every time I try to access PuTTY, I get a black window with one green square and not able to input any kind of data...

What do I need to do to get access to my server using PuTTY? I can connect with my iPad, so no issues connecting to the server...

EDIT:
This is what my netstat looks like:

This is most likely not the answer you want, but if your network admin has correctly configured the proxy, then you can't connect through it.

I am guessing they don't want to allow non-http(s) traffic, so there won't be much you can do about it. You could try running your ssh server on port 80 or port 443 and see if they allow you to connect to it that way.