as my crystal ball is in the dishwasher today, it would be good to have a minimal working example (showing what you've tried so far) and some more details on the situation you're in. For example, you may need to do different things in order to load a font depending on what TeX engine you're using.
For ordinary pdfTeX, you'd do the following:
\documentclass{scrartcl}
\usepackage[T1]{fontenc}
\usepackage{tgpagella}
\usepackage{eulervm}
\begin{document}
lorem ipsum
\begin{equation}
a^2 = b^2 + c^2
\end{equation}
\end{document}
...while with LuaTeX, you'll need something like:
\documentclass{scrartcl}
\usepackage{fontspec}
\setmainfont{TeX Gyre Pagella}
\usepackage{eulervm}
\begin{document}
lorem ipsum
\begin{equation}
a^2 = b^2 + c^2
\end{equation}
\end{document}
