Create Checking Permission function in LINQ C#

I create 1 loginForm, this form will check email and password, if them typed like info in database, redirect to mainForm.
Addition, I want to create and check id, if id = ‘1’ => admin, show mainForm, if not show Error Msg.
Because anyone can Login and manage info in database
my database have 1 table included 7 fields: id, email, password, fullname, sex, birth, address
AccountBUS.Cs:

AccountManagementDataContext AccMgr = new AccountManagementDataContext();
        public bool CheckLogin(string email, string password)
        {
            int account = (from acc in AccMgr.BasicInfos
                           where acc.email == email && acc.password == password
                           select acc).Count();
            if (account == 1)
                return true;
            else
                return false;

        }
        public IEnumerable<BasicInfo> SelectAll()
        {
            IEnumerable<BasicInfo> account = from acc in AccMgr.BasicInfos
                                             select acc;
            return account;
        }
        public bool CheckAccount(string email)
        {
            int account = (from acc in AccMgr.BasicInfos
                           where acc.email == email
                           select acc).Count();
            if (account == 1)
                return true;
            else
                return false;
            
        }

How I can make checking id function?