Worksheet change event for range of cells

[Santosh123]

I have some issues while working on Worksheet change event for range of cells.
I have one sheet in which user have to update required fields and
click on send email command button which sends mail.
I have assigned sending email macro to command button And other data is stored from range A4:H7(this range is not constant.May
vary in other sheets).
Now there are three last columns and Send email command button for which i need help
Column F-- Status Column-- Data validation is done so only allows values Active or Inactive
Coolumn G- Effective Inactive Date--This column is blank. This value should be entered when column F values is selected as
Inactive.
Column H - Review -- Data validation is done so only allows values Yes or No

Now I require following things working:
1. Column F:Status Column --> a. If user selects Inactive value then message box should pop up asking user to enter susbsequent Effective Inactive Date value.

b.Also want subsequent Effective Date value made mandatory for user if status is Inactive.

c. If field in this column is left blank then Command button(here SendEmail) button should not work and one message box should pop up upon clicking command button asking user to update require fields


2. Column H: Status -->
a. If field in this column is selected as No or left blank then Command button(here SendEmail) button should not work and one message box should pop up upon clicking command button asking user to update require fields

 

[Santosh123]

anyone have any clue? please help me to solve this problem