Stuck at table function

Dept_No (Int)
Dept_Name (Char(30))

and using the following database:

EMPLOYEE (fmane, minit, lname, ssn, birthdate, address, sex, salary, superssn, dno)     KEY: ssn
DEPARTMENT (dname, dnumber, mgrssn, mgrstartdate)               KEY: dnumber.
PROJECT  (pname, pnumber, plocation, dnum)                          KEY: pnumber.

I'm stuck at right now, want give me some advice on starting it? really don't know where to start

Select e.Dept_No, d.Dept_Name, Count(e.Dept_No), 
SUM(e.salary) as Sum_Salary,
AVG(e.salary)  as AVE_Salary
from EMPLOYEE e
join DEPARTMENT d ON e.dno = d.dnumber
Group by e.Dept_No, d.Dept_Name

• First you need to join dept and emp tables.
• Since you need total salary by dept you have to group by dept no
• also you want to show dept_name so you have to group by it as well
• If you have columns except functions(avg,sum.. etc) you have to add these columns group by statement.