Form and loop to enter data

[gipsyfkls14]

Hello Community.
I have been trying to write a VBA code as an example to learn. I included Excel Wb
In example attached (Excel 2010), User enter data in column C and Column E

I need:
For the first time when user enters data in Colum C and Column E cmb PEES works.
When user enters more data in Column C and column E, cmb PEES must works.
Code_Number (B2) must be entered only once a day. At present I enter data for the first time.
However, I need user enters such data in txtCode in the Form.
In column A when user enters data in Column C and Column D actual date is written but not with new data
Finally, I have been trying to format data as in row2 but all attempts aborted.
I apologize if the above text t is confused; English is not my mother tongue.
Any help is welcome