You must have Microsoft Visual Studio Tools for Office installed (VSTO).
In the Visual Studio installer, choose VSTO from the Workloads > Web & Cloud > Office/SharePoint Development menu.
Then, using the 'Add Reference... > Assemblies' window, create a generic.NET project and reference Microsoft.Office.Interop.Excel in it.
Application excel = new Application();
Workbook wb = excel.Workbooks.Open(path);
Missing.Value is a special reflection struct for unnecessary parameters replacement