Want to design a userform And codes

I have a workbook that have three excel worksheets front-sheet, data and function ....
I want to design Two button that open user-form in my front-sheet the first button Called Calculate that show me the userform that contain the headers of Function sheet (you can see my formula in function sheet) and The second Button make inquiry about employers "by code and salary date" that give me information i entered before by calculate button and i can to modify it .
any help and response will be thankful and i appreciate that .
especial thanks to BSB who help me in the workbook
please any codes and answer in the same workbook.
mak_pj