After the "START" button pressing you will be prompted for permission to access your microphone. The confirming icon will appear in the right bottom corner of the text box indicating that the system is ready for voice dictation. Now you can start your speech.
As long as you speak the system is recognizing your speech and the result will immediately appear in the text box. For better recognition try to pronounce words as clearly as possible. If you are not satisfied with results you may try to reduce the speed of your speech.
During the speech recognition the system is trying to get the closest meaningful phrase. Therefore, if a word you see is not exact the same that you have said, do not stop talking. Finish the speech or a sentence and most likely the final version of recognized text will be much closer to the original one.
To stop voice recognition software you can either press the "STOP" button or just stop talking (voice recognition software stops in a few seconds). All the recognized text will remain in the text box. Now you are able to edit if necessary, copy and use for other purposes.