Currently Being ModeratedApr 7, 2013 6:56 PM (in response to Luis Ventura)
If you mean RAM, you can't except when configuring a model which hasn't left the factory.
If you mean drive space, purchase and connect an external drive, or upgrade the internal one.
Currently Being ModeratedApr 7, 2013 6:57 PM (in response to Luis Ventura)
No, you cannot upgrade the ram in a MacBook Air.
But if you mean increase mass storage space, you can remove unneeded files or add an external hard drive and move you files to that drive.