Here's a step-by-step guide on how to insert data into an SQLite database in C#:

1. Install the System.Data.SQLite NuGet package:

Install-Package System.Data.SQLite

2. Create an SQLite database:

using System.Data.SQLite;

class Program
{
    static void Main()
    {
        string connectionString = "Data Source=YourDatabase.db;Version=3;";
        SQLiteConnection.CreateFile("YourDatabase.db");
    }
}

3. Open a connection to the SQLite database:

using System.Data.SQLite;

class Program
{
    static void Main()
    {
        string connectionString = "Data Source=YourDatabase.db;Version=3;";
        using (SQLiteConnection connection = new SQLiteConnection(connectionString))
        {
            connection.Open();
            // Insert data here
        }
    }
}

4. Insert data into the database:

using System;
using System.Data.SQLite;

class Program
{
    static void Main()
    {
        string connectionString = "Data Source=YourDatabase.db;Version=3;";
        using (SQLiteConnection connection = new SQLiteConnection(connectionString))
        {
            connection.Open();

            string insertSql = "INSERT INTO users (username, email) VALUES (@username, @email)";
            using (SQLiteCommand cmd = new SQLiteCommand(insertSql, connection))
            {
                cmd.Parameters.AddWithValue("@username", "john_doe");
                cmd.Parameters.AddWithValue("@email", "[email protected]");
                cmd.ExecuteNonQuery();
            }
        }
    }
}

5. Close the connection:

connection.Close();