After launching MobiPDF, go to “Home → More”.
Choose the type of conversion you want to perform from the list of available options.

TIP: You can also access the same functionality by opening a PDF and clicking on the “Convert” tab in the upper ribbon.
If you accessed the converter from the "Home" menu, choose a file that you want to convert and where you want to save it on your device. In case you already have your document open, simply choose where you want to save the final output.
Enjoy your newly converted file!