Add settings for new plugin

My plugin is similar to NEWS module. How can I save to these settings? Do I have to add some (setting) rows to DB manually?

public class ContentSettings : ISettings
    {
        /// <summary>
        /// Gets or sets a value indicating whether Content are enabled
        /// </summary>
        public bool Enabled { get; set; }

        /// <summary>
        /// Gets or sets a value indicating whether not registered user can leave comments
        /// </summary>
        public bool AllowNotRegisteredUsersToLeaveComments { get; set; }

        /// <summary>
        /// Gets or sets a value indicating whether to notify about new Content comments
        /// </summary>
        public bool NotifyAboutNewContentComments { get; set; }

        /// <summary>
        /// Gets or sets a value indicating whether to show Content on the main page
        /// </summary>
        public bool ShowContentOnMainPage { get; set; }

        /// <summary>
        /// Gets or sets a value indicating Content count displayed on the main page
        /// </summary>
        public int MainPageContentCount { get; set; }

        /// <summary>
        /// Gets or sets the page size for Content archive
        /// </summary>
        public int ContentArchivePageSize { get; set; }

        /// <summary>
        /// Enable the Content RSS feed link in customers browser address bar
        /// </summary>
        public bool ShowHeaderRssUrl { get; set; }
    }

You need to inject the SettingService into your Controller and other classes that need access to settings.

Look at an existing plugin like Shipping.ByWeight.

...\src\Plugins\Nop.Plugin.Shipping.ByWeight\Controllers\ShippingByWeightController.cs

            _shippingByWeightSettings.LimitMethodsToCreated = model.LimitMethodsToCreated;
            _shippingByWeightSettings.CalculatePerWeightUnit = model.CalculatePerWeightUnit;
            _settingService.SaveSetting(_shippingByWeightSettings);