|define a global variable counter as integer|
create a FOREACH loop for each row in the database
in the loop you'll check to see if the specific cell in that specific row has the data "Yes" in it. if so, counter++ (or maybe counter += 1) else do nothing
as soon as the loop is finished you'll output your counter variable wherever you need it; lblCount.text = counter.tostring()
alternatively some people don't like global variables (they're evil!) You could do the same thing but instead of incrementing the counter variable (as you're not using one) during each loop iteration you would do something similar to:
lblCount.text = (lblCount.text.toInt + 1).tostring()
I dont know for sure if that exact syntax will work in vb.net as I typically use C# that's the idea.