First things first, look around and see what's out there and available. For your convenience there are some links below to help you get started on your quest for music samples. Alternatively, you can go to your favorite search engine and do a search on 'free techno beats'. Just keep looking around and see what all you can find.
Next, before downloading anything, make sure to read everything such as the terms of use or licensing agreement to make sure that the beats, loops or sample files are not only free but are royalty-free so that you are allowed to use them in the manner you want.
Take precautions against spyware and viruses before downloading any of your techno music files as it's a very easy way to get infected or malicious files on your computer. Only use sites that you trust.
Keep your techno beats and loops that you download in separate files according to their sound, format (for example .wav or .mp3) and organize them by the instrument they represent. Such as, keep a separate file for techno drums, and then a separate file for keyboards and synths or sound effects. This will save you a lot of time down the road when you are creating music as all these loops and samples add up really quickly and if you don't keep them organized they are a mess to go through and can slow you down when you are creating your techno music.