Decryption

I'm working on a website. We're all volunteers and we don't have any money to buy a ssl-certificate, which should be the way to do this. Still I would like to send some encrypted data to and from the server and decrypt it again.

I will probably use http://www.planet-source-code.com/vb/scripts/ShowCode.asp?txtCodeId=8967&lngWId=4 to do the encryption from user to server.

My problem now is to send information back from the server to other people, without any security holes. So I need the reverse: send encrypted info from the server and decrypt it at the client.