Based on your comments, it seems you are asking how to find a lawyer in Austria. There is a bar in each province (Bundesland) and they work together through something called the Rechtsanwaltskammertag. Its website provides a way to search for lawyers by area of expertise. Unfortunately the web form (and in particular the list of legal areas/specialities) is only available in German.
However, it's possible to look for lawyers who speak another language than German, which is particularly useful for expats. You need to select your language in the Fremdsprache drop-down list in the widget. For example, here is a list of Italian-speaking lawyers who reported being specialized in transport law and accident damages.
Beside the convenience of being close to your lawyer, it might be particularly important to hire a local lawyer as Austria is a federal state and traffic fines are typically defined at the provincial level.
Note that as far as I know, pure contingent fees are forbidden in Austria (and in many other European countries), so irrespective of the merits of your case there is probably no free way out as you might need to pay both the fine itself and lawyer fees upfront even if it gets tossed out later. One practical way to avoid even greater problems could therefore be to pay up before the fine is raised and avoid parking where you shouldn't going forward. You could also become a member of the local automobile club as they offer some legal advice to members.