Beginners Guide to FLDIGI
What is Fldigi?
Fldigi is a computer program intended for Amateur Radio Digital Modes operation using a PC (Personal Computer). Fldigi operates (as does most similar software) in conjunction with a conventional HF SSB radio transceiver but in this case you will be linking it to Zello(radio), and uses the PC sound card as the main means of input from the radio, and output to the radio. These are audio-frequency signals.
Fldigi is multi-mode, which means that it is able to operate many popular digital modes without switching programs, so you only have one program to learn. Fldigi includes all the popular modes, such as DominoEX, MFSK16, PSK31, and RTTY.
http://www.w1hkj.com/beginners.html
YouTube clip beginners guide to FLDIGI: