I don't really understand your last question. Are you saying that you bought a domain (for example
www.mydomain123.com), but when you type that domain into the browser your site doesn't show up?
If you've already parked the domain like you mentioned, you still have to change the nameservers. You need to ask 1&1 hosting for the necessary nameservers and then you need to go to the domain registrar you bought the domain name from, login, and change the nameservers accordingly.