If you look at
SQLiteDataReader class docs, it has methods like:
GetString(index)
GetInt32(index)
So you need to create a new user e.g.
UserList.Add(new User()
{
Name = reader.GetString(0),
LastName = reader.GetString(1),
});
If you are just starting with C#, may I recommend looking at Entity Framework Core, it can simplify database operations.