How do you get the count of records in a db with Entity 4

I'm trying to get the count of the total number of  departments in my db.  but I don't know how to do this with entity. below is what I have and I'm stuck.

Code for button click event:

OrgEntities OE = new OrgEntities();
 tbl_Dept d = OE.tbl_Dept.Count()

Lbl_deptCount.text = d.ToString();

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Sample of what I'm Trying to do with Entity:

SELECT *  FROM tbl_Dept  WHERE Did = 2

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