If all you need is a list of nodes by the current user, the easiest way is to use the User:Current filter. Just click the [+] next to 'Filters', choose 'User:Current' from the list, click the 'Add' button and set the filter to 'Yes'.
The argument-method as described by streetparade (using the 'User: Uid' argument) is useful if you want users to see the list of other users as well. Suppose that your view's url is www.example.com/my-content. If you add a user argument, user #3 could see what user #7 has posted on www.example.com/my-content/7. If you want that, use the argument. If you do not want that, use the filter.