html tags and python

Hi all

I am making something for my webpage

Where the user can choose a month: I have made that with a dropdown box.

 <select>
        <option name = "1" value="1">January
        <option name = "2" value="2">February
        <option name = "3" value="3">March
        <option name = "4" value="4">April
        <option name = "5" value="5">May
        <option name = "6" value="6">June
        <option name = "7" value="7">July
        <option name = "8" value="8">August
        <option name = "9" value="9">September
        <option name = "10" value="10">October
        <option name = "11" value="11">November
        <option name = "12" value="12">December
        </select>

The thing is:
I also want the user to choose a date
I will make this with another dropdownbox.
But if the first month is selected, then there should be 31 days in the days
dropdownbox, if the second month is selected there should be 28 days in the
dropdownbow.

I Know a little of python programming, but not to much, I have a feeling of 
that I should use a cgi, can any explain me what I have to do :?  Or give me 
a link to a site where I can copy the code for it

All help will be greatly appreciated.

Thanks for your time