Navigate in your browser to https://connect.bentley.com and select your connect project and the iModel for export. Note that the features available through the Connect Portal are limited and new functionality is being added only to the iTwin Portal described below.
The IFC Export dialogue will appear. The folder structure displayed comes from the Project Share for this particular Connect Project. Select the folder where the generated IFC file will be stored.
You can select to use have the IFC file user either the 4.3 RC1 or 2X3 format.