Hi Mikofi,
If you have electronic knowledge, then you can try to buy some simple electronic security kits such as door contact, motion sensor, smoke alarm and install it according to instruction. Many sellers provide video guide and you can follow.
If you do not have electronic knowledge, then you should get knowledge of it. For example, you should known the basic of alarm system including the meaning of terms. And it may be hard for you to start from beginning except for you are an electronics enthusiast and often DIY electronics.
