Type of sensor needed

Hi I really like this system you have created.  I would like to install this system in my new garage at this point there is nothing for security and I want to go wired with WiFi which is installed in the garage. Question is I will have to purchase some new door and window sensors along with motion sensors is there anything special I should look out for when making the purchase voltage type? Would anyone have any suggestions where and type to purchase in Canada. Thanks