If I understood your question correctly, for the first part you could use a query like
SELECT *
FROM Task
WHERE DayOfWeek = DATEPART(weekday, GETDATE());
And for the second part if you have a column named Day in the same table and you have a row where Day is 12, to check if today is 12th something like:
SELECT *
FROM Task
WHERE Day = DATEPART(day, GETDATE());