query_posts with custom field (filter by day)

I am wanting to display posts with a custom field using query_posts.

The custom field would be a specific date which is entered by the user. The function would have to figure out if this date is a saturday or sunday and show only these posts.

For example; on my landing page I want one column of posts with ‘custom field = saturday’ and one column of posts with ‘custom field = sunday’ and no others.

I have already looked over the documentation for ‘query_posts’ and ‘custom fields’ but am still finding myself rather confused. I am very very new to php and learning as I go along. Any help or pointers that anyone can provide would be very helpful.

Thanks.