All dates contain year, month and day, but can be displayed in a variety of ways. Excel actually stores these as a single number (serial date). If you change the cell format of a cell containg a date to GENERAL you will see a number. So the format of your cell is actually Date format not text.
18/03/2008 is actually 39525. So 39526 is the 19th March (39525.5 is midday on the 18th - get the idea?) .
Dates are handled differently in VBA. For example on a worksheet
=TODAY() return todays date and
=TODAY()+1 returns tomorrows date.
In
VB TODAY is replaced with DATE so the line would read
myvariable = DATE
This can be confusing as the worksheet uses DATE in a different way
=DATE(year,month,day).
If all you want to do is check if one date is after another (ie greater than) use a simple if statement
if range("C19")>range("C17) then dosomething....
if you have multiple entries to check the use a FOR TO loop to check each on
for f=1 to 10
if range("C" & f )>range("C" & f+1) then dosomething....
next f
To use the slash in the code you would need to use something like this;
MyDate = Range("C12")
If MyDate < #1/1/2008# Then MsgBox ("Hello") Else: MsgBox ("Goodbye")
Bear in mind that you don't want to change the code every day so you need to pick up the relevant date automatically.
Finally, do a web search on 'using dates in vba', there are loads of sites with handy hints and tips. the ones that are ten years old contain the best information for the beginner (even if the pages look awful).