validations in Csharp using if loop

Question

hiee All...iam new to C sharp.

i have one combobox,2 date picker one for from date and one for to date.i have also 4 checkbox

my requirement is i want to validate all this controls in a windows form using if loops and using operators.

i.e if i leave my controls it shd show everycontrol which is empty in one message box...not in multimessage box...
if i enter combobox.....the other controls which are left blank ...an error message with all controls left empty in one mesage box shd be show..


i hope i will get a help on this.....thank u all and respect to all the people here....