The entry point to the APIs is in the AtomicAssetsApiFactory. You can initialise any supported API from there. You can then call any endpoint from the initialised API. Each endpoint has its own set of parameters that you may build up and pass in to the relevant function.
var assetsApi = AtomicAssetsApiFactory.Version1.AssetsApi();
var assets = assetsApi.Assets();
assets.Data.ToList().ForEach(a => Console.Write(a.AssetId));
1099567200114 1099567200113 1099567200112 1099567200111 1099567200110 1099567200109 1099567200108 1099567200107 1099567200106 ...
var assetsApi = AtomicAssetsApiFactory.Version1.AssetsApi();
var builder = new AssetsUriParameterBuilder().WithLimit(1);
var assets = assetsApi.Assets(builder);
assets.Data.ToList().ForEach(a => Console.WriteLine(a.AssetId));
1099567200114