Before you begin you must make sure that you use the right tools for the job. Read this site carefully with all it's instructions waiting for you to get you going on this journey of DIY domotica. Make sure you read the wiki before buying a sender or receiver for your Raspberry Pi:
If you still decide to buy the second you cannot expect the community to help you out because it's not supported.
So, buy the right tools for the job and get started!
Any questions because you cannot find it in the wiki or on this site? Try to get help on the forum or just contribute by helping others.
A receiver needs a good band-pass-filter. If you want to get started quick read this , and get going without any hassle!