Looking for casual sex relations

We are a Spanish couple just moved to Copenhagen. We never had sexual meetings with other couples, groups or made dogging, but all of them are in our fantasies. As have now some freedom (our daughters are in Spain), perhaps we could be introduced in this new sexual world. We would like to start in the right way to have a good experience starting as softest as possible, so also an advise for some other couples that had started like us only with fantasees, but with some fear to make them reality will be also appreciated and helpful. My main fantasy is to see how other young guy is making love to my wife in my presence and she likes to have sex with other woman. So we are now in the point where we can do the first step or do it never. :-)