Take some money from everyone who can afford it, and more from the rich than everyone else. Redistribute it into education, roads, healthcare, food, research, national defense, police, and other things that benefit society as a whole (including the rich).
You might want to do some research on what socialism actually means, because though it includes the above, it is not defined by the above. You can tax and spend that money on social (and other) services, while retaining a capitalist economy. Which is what we and every other developed nation does.
Socialism is state control of the means of production, which though it does happen with certain industries in some countries (usually energy related), it's pretty rare.