= Introduction by example =
You need a data range and instructions how to handle the data. An example:

At https://www.cpb.nl/cijfer/actualisatie-middellangetermijnverkenning-2018-2021-verwerking-regeerakkoord a spreadsheet wit data can be downloaded. In 2017 we are interested how much money Dutch people will pay for medical insurance in the future. A CSV file is generated with name "CPB_Nominale_zorgpremie". It contains:

{{{
2006, 926
2007, 1001
2008, 1049
2009, 1059
2010, 1095
2011, 1199
2012, 1226
2013, 1213
2014, 1098
2015, 1158
2016, 1199
2017, 1290
2018, 1359
2019, 1431
2020, 1526
2021, 1601}}}

From a terminal gnuplot is started:

{{{
wiebe@wswl:~$ gnuplot

	G N U P L O T
	Version 5.0 patchlevel 3    last modified 2016-02-21 

	Copyright (C) 1986-1993, 1998, 2004, 2007-2016
	Thomas Williams, Colin Kelley and many others

	gnuplot home:     http://www.gnuplot.info
	faq, bugs, etc:   type "help FAQ"
	immediate help:   type "help"  (plot window: hit 'h')

Terminal type set to 'qt'
gnuplot> set size ratio 0.5
gnuplot> plot 'CPB_Nominale_zorgpremie' with linespoints
gnuplot> }}}

The range is plotted in a new window and from there you can export to SVG (first button top left).

If you're not happy with the results you can post edit in Inkscape. The result should be:

{{attachment:CPB_Nominale_zorgpremie.svg}}

= After you got the taste of it =
Creating a plot is very easy as you can see. Searching the net is not as useful as expected, many people see gnuplot as some sort of "higher art". Possibilities are endless.

What to do for a basic understanding? RTM! Go here: http://www.gnuplot.info/documentation.html