Speech recognition software can be very pricey, but adding a speech
recognition option to your computer doesn’t have to be expensive. Here are two free speech to text tools to try.

In Google Chrome you can use the Speech Recognizer app available for free through the Chrome Web Store. To use the Chrome Speech Recognizer
just install it from the Chrome Web Store, launch it, then click the
microphone to start taking and recording your voice. The Speech
Recognizer will type out your text when you finish recording. You can
then copy and paste your text to the paragraph box below the Speech
Recognizer or to a document you have open in Google Docs.

Online Dictation
is a free site that will transcribe your speech for you. To use the
site just visit it, click on the microphone icon, and start talking. If
the transcription inserts the wrong word (for example it inserted
“number” instead of “mumble” when I tried it) just click on that word to
replace it. You can copy the transcript and paste it anywhere you like.