My son's school district uses and .us address, can get thim enrolled

As you can imagine, a county named “Jefferson” is prevalent in the US. As such, the Colorado Jefferson County Schools district uses and the online system won’t let him register… I can’t find a “contact us” so I’m hoping I can get some advice here… I might just not be smart enough to find the contact us info… Ugh… feeling like a stupid developer trying to teach my kiddo.