1. Opening by specifying file name. Select ADO interface, then choose File option and then browse for the needed file.
2. Opening through connection string. Select ADO interface, then choose Connection string option and write a connection string. This way is very flexible and allows to specify additional parameters in the connection string and override standard Reportizer connection behavior. It is recommended for advanced users. Here are basic connection strings (more examples and details can be found in the Internet):
Provider=Microsoft.Jet.OLEDB.4.0;Extended Properties="HTML Import;DATABASE=C:\MyData\MyHTMLFile.html";