|Providing the date is formatted as date and not a string all you need do is simply add 30.|
Dates are stored in Excel and nearly all Windows applications as a floating point number. The part before the decimal point is the number of days since 31 December 1889, hence 0 January 1900 which equals zero. The 1 January 1900 is day one in the Windows calendar.
The part ofter the decimal point is the number of seconds since midnight.
So the formula would simply be: =+A1+30
BTW: January 9, 2006 plus 30 days is February 8, 2006