To export a plot, assign a variable to the plot; for example graph1=ListPlot[c], and then export using Export["filename.jpg",graph1] to save the plot as a jpeg, with the chosen file name, in whichever folder is set as default in Mathematica’s properties (to set the target directory type SetDirectory["dir"] or place the full file path in the Export function).

Some basic Mathematica info, mostly to stop myself having to continually research things that I should already know. Basic syntax to start.

(*comment*) code comments should be between (*
“string”a string is defined by quotation marks.
a is an assignment.
2*10^5 standard form (replaces the usual 2e5).
esc phi esc greek letter phi.
Sin[0] functions begin with a capital letter with their arguments in square brackets.
{x1, x2, x3} list of variables....