Making a Login Form Connected to a DB

Question

I've been trying to teach myself how to do this for a few days now but can't figure out certain things.

 

This is what I have currently and I can't, for the life of me, figure out where I'm wrong at. I hope this isn't a lost cause as I'm trying to help my school get out of using paper for certain things and this is my first step.

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.Data.Sql;
using System.Data.SqlClient;
namespace CCCLogin
{
public partial class Form2 : Form
{
public Form2()
{
InitializeComponent();
}
private void Exit_Click(object sender, EventArgs e)
{
this.Close();
}
private void Login_Click(object sender, EventArgs e)
{
SqlConnection con = new SqlConnection(@"Data Source=(LOCALDB)\MSSQLLocalDB.C:\USERS\MICHAELC0837\DOCUMENTS\CCCLOGIN\CCCEMPLOYEES.mdf; Initial Catalog=CCCEMPLOYEES.mdf; Integrated Security=True");
SqlDataAdapter sda = new SqlDataAdapter("select count(*) from Username where username='" + UserTxtBox + "and password='" + PassTxtBox + "'", con);
DataTable dt = new DataTable();
sda.Fill(dt);
if (dt.Rows[0][0]).ToString() == "1")
{
this.Hide();
CCCLogin ss = new CCCLogin();
ss.Show();
}
else
MessageBox.Show("please enter correct username and password", "alert", MessageBoxButtons.OK, MessageBoxIcon.Error);
}
}
}
}