It will be hard to speak of "the" postmodern view of gender. There are many differences of opinion. However, there are a few principles of postmodernism that are important to consider when you are talking about gender or any other topic.
First, postmodernism does not believe in a meta-narrative or a dominant discourse. For example, Foucault talks about the archaeology of knowledge. So, when we apply this to gender, then postmodernism would question the legitimacy of masculine narratives and views of the world.
Second, postmodernism is also very sensitive to issues of power. For this reason, it will question the male power structures that are in place, such as male ideology, which often times makes masculine power seem "just the way it is."