those who not logged in last 7 days and 15 days.. .....need oracle query

Hi
guys
i have one table..i need oracle query for those who not logged in last 7 days and those who not logged in last  15 days.
I am storing login time in "LEDIT " column.
.kindly help

1>users
USER_CODE    VARCHAR2(20 BYTE) USER_NAME    VARCHAR2(60 BYTE) USER_DESIGNATION    VARCHAR2(60 BYTE) USER_PASSWORD    VARCHAR2(20 BYTE) OFFICE_CODE    VARCHAR2(20 BYTE) USER_LEVEL    CHAR(3 BYTE) USER_PICTURE    BLOB USER_DESCRIPTION    VARCHAR2(100 BYTE) FONT_PREFERENCE    VARCHAR2(25 BYTE) ID    NUMBER(11,0) LEDIT    VARCHAR2(100 BYTE)
2>OFFICES
OFFICE_CODE&nb ...