how is the first reader introduced to mildred? how do the descriptions of her and her actions characterize her?

The reader is introduced to Mildred when Montag returns home from work only to find she's overdosed on sleeping pills. When we next meet her (the next morning), she has no memory of the events. This would lead us to characterize Mildred as a rather sad, uncaring woman. She's bored with her life and living.