How do I pre-select check-boxes or radio buttons in my questions?

I'm working in SSI Web 7 and would like to pre-select some graphical check-boxes or radio buttons on some of my questions. Here's my problem. First, I want to set the check-box in the first row and first column of a grid question to be on when the respondent first sees this page. Second, I want to pre-select a specific radio button in a select question. How do I accomplish these two tasks?