Regarding digital modes, there are many, many of them, but one of the PSK-31 is a very popular one, or at least was popular until usurped by FT8. One of the most popular *free* interfaces is called FLDIGI. This can be found on the web at:

• https://sourceforge.net/projects/fldigi/

 A long list of descriptions of digital modes, and software available is here:

• http://wb8nut.com/digital/

Appearance on a waterfall and sounds are here:

• http://www.w1hkj.com/FldigiHelp-3.21/Modes/

K7AGE’s intro to PSK-31 is very good.  There is a link on this page as well.

• http://www.hamblog.co.uk/top-10-psk31-tips-for-beginners/