How to "check" a check box?

I'm trying to make some my own engines and I've got problem with "checking" a check box. For example here: http://www.biblionetka.pl/nu.aspx you've got a checkbox "Akceptuję regulamin serwisu BiblioNETka.pl" (I accept terms and rules). Can somebody please help me with this?

Use the following:

ctl00$MCP$CUW$CreateUserStepContainer$RulesAccepted=1

or

*RulesAccepted=1

---

<formvariable or mask>=1 << 1=checked, 0= unchecked, anything else=checked if matches the label

I would use

ctl00$loginUser$RememberMe=on

You'll find using firebug or httpfox on firefox useful for showing you exactly what data is sent when submitting a form

Whoops wrong field lol

Thank you guys!