Why would you want to do that ? Let the OS manage the RAM. Free RAM is wasted RAM.What are some ways to free up RAM on my wife's MBA 11" with 2GB? Even idle, it only has about 512 free.
$ sudo purge
Don't bother with any of the apps that are available either free or paid, they do nothing really. OSX will take care of the usage of memory. As the previous post explained you have to understand the way memory usage is displayed. If you are really out of RAM, OSX will page out to disk, it will slow things down but i doubt you'll notice much impact as it's paging out to your SSD rather than a spinning disk.
Wired means RAM that is permanently in use and cannot be freed.