Here is a select statement that will meet your requirements:
--Test Data
CREATE TABLE #User ( uid int
, FirstName varchar(50)
, LastName varchar(50)
, Email varchar(50)
, Username varchar(50));
INSERT INTO #User(uid, FirstName, LastName, Email, Username) VALUES(1,'MackF','MackL','mack@mack.com','MackUname');
INSERT INTO #User(uid, FirstName, LastName, Email, Username) VALUES(2,'2F','2L','2@mack.com','2Uname');
INSERT INTO #User(uid, FirstName, LastName, Email, Username) VALUES(3,'3F','3L','3@mack.com','3Uname');
INSERT INTO #User(uid, FirstName, LastName, Email, Username) VALUES(4,'4F','4L','4@mack.com','4Uname');
CREATE TABLE #Follows( rid int
, FollowedName varchar(50)
, FollowingName varchar(50));
INSERT INTO #Follows VALUES(1,'4Uname','2Uname');
INSERT INTO #Follows VALUES(2,'MackUname','4Uname');
INSERT INTO #Follows VALUES(3,'4Uname','3Uname');
INSERT INTO #Follows VALUES(4,'MackUname','3Uname');
--Query
SELECT u.Username
, u.FirstName
, u.LastName
, u.Email
, COUNT( f.Followingname ) AS followercount
FROM #User u
LEFT JOIN #Follows f
ON u.Username = f.Followingname
WHERE uid NOT IN (2,4)--here is where your WHERE clause goes remove this line to see all records
GROUP BY u.Username
ORDER BY followercount DESC
--Results
USERNAME FIRSTNAME LASTNAME EMAIL FOLLOWERCOUNT
3Uname 3F 3L 3@mack.com 2
MackUname MackF MackL mack@mack.com 0
Here is a SQL fiddle to try it all out.
NB: I have renamed your column "count" to "followercount" as COUNT
is a reserved word.