How do i get section number and names in my heading? - latex

Question

I'm new to LateX but I'm starting to get a hang of it but I have some problems.. I would like to have section number in my header but I don't know how to do it. I'm using the fancy package and writing in article class. I have seen some solutions to make this work in Book settings but I like the article class better.
\documentclass[12pt,a4paper]{article}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage{amsmath}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage[danish]{babel}
\usepackage{graphicx}
\usepackage{graphics}
\setlength{\parindent}{0in}
\usepackage{subfigure}
\usepackage{a4wide}
\usepackage{pifont}
\usepackage{float}
\parindent=0pt
\usepackage{eso-pic,fix-cm,ae,aecompl,ifthen,color}
\usepackage{fancyhdr}
\pagestyle{fancy}
%
%
%
\begin{document}
%
\fancyhead[C]{ \thesection}
\fancyhead[L]{}
\fancyhead[R]{}

Answer 1

In the following a part of the headings I use. Hope, it's helpful.
\documentclass[12pt,a4paper]{scrartcl}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage[danish]{babel}
\usepackage{scrpage2}
\begin{document}
\pagestyle{scrheadings}
\clearscrheadfoot % clear default settings
\setheadsepline{1.5pt} % seperator line between heading and text
\newcommand{\headsection}{\thesection\ \leftmark} % <number of section> <section name>
% \newcommand{\headsection}{Section \thesection} % Section <number of section>
\renewcommand{\sectionmark}[1]{ \markboth{#1}{} }
\lohead{\headsection} % actual section
\ohead[]{\pagemark} % page number
\section{Introduction}
\newpage
\subsection{subsection 1}
\newpage
\section[Title of section in heading]{Main}
\newpage
\subsection{another subsection}
\newpage
\end{document}