Before you start, please provide token and user id in appsettings.json. If there's no appsettings.json then create it in project folder (folder where .csproj file located). It should be as the following:
{
"Creds": {
"BotToken": "", // Your bot's token which you can get from https://t.me/BotFather
"UserId": 0 // You can get your user id using bots such as https://t.me/userinfobot
}
}