Hardware advice for simple wireless embedded application
Since you are new to microcontrollers, your best course of action would be to get an Arduino (there are several types).  While they are designed for beginners, they also have a lot of flexibility.


Peripherals for the Arduino are called shields, and they have many options for doing wireless.  One option you might want to consider is Bluetooth, which can cover up to 100m out in the open, and quite a bit less indoors. You didn't say whether you will be indoors or outdoors.  There are many Bluetooth shields, such as this one.  In almost all cases, the antenna is already included on the board.

If battery life on the remote device is a factor, you might also want to investigate Bluetooth Low Energy, which has a range similar to "classic" Bluetooth but consumes much less power.  It is quite new (there is no native support for it in Windows 7, for example), but since you will be providing both ends of the wireless link, this should not be a problem.