There are many ways to win in terms of voting. The most common ways is with plurality. Who ever got the most votes has the plurality. This is often the most common for kids, though it can be unfair. For example, if I got most of the votes, but I only have 33%, I may have won the plurality, but 77% of the people did not choose me.
When coming to elections of the president and other high offices, often times a majority is required. That is when at least one person received more than half of the votes. The idea of asking for a majority is to guarantee that most people are getting what they want.
Even further, a supermajority is a determined number above a majority, such as 2/3 of the vote or 3/4. This is the case when overriding a veto (2/3) or making an amendment (3/4) to the constitution. The idea of supermajority is to make the vote very difficult so that change can not happen too quickly.