Basically what you need to do is copy your public key to the authorized keys file on the server. If you haven't got a public key yet just type in:
ssh-keygen -t dsa
And that will create an id_dsa.pub file in your ~/.ssh folder (By default, you can set it in other places if you want). Anyway, copy the content of that file (it should be just one line) into the ~/.ssh/authorized_keys file on the server you want to login. Now whenever you ssh username@server you'll access it straight away without any password. And scp also works without password so you can write those scripts.