passive with amp?

[Rodel]

I have passive speakers that can handle 4 watts and I want to connect and amp on it. How do I do this and how do I build the amp?

[sofaspud]

It seems obvious that you are a beginner. Nothing wrong with that - we all started there.
Your second question has an easy answer. The speakers connect to the + and - of the amp outputs, like a battery.
Your speakers are rated for 4 watts which is considered low-power. You also need to know their impedance rating. This is likely to be either 4 or 8 ohms. Once you know the speaker impedance, have a look around the internet for a suitable low-power amp.
As a beginner it might be a good idea to start by building from a kit. The kit will provide you with a printed circuit board and the parts you need. There are many sellers of kits on the web. If you find something that looks promising, you can double-check by asking here.
If you feel you are up to it, you could build an amp from scratch using an audio IC such as the LM380 or LM384. There are many others that you could use. Datasheets and application circuits are available online, and these chips are relatively easy to work with.
Since your amp will be low-power, you can use a "wall wart"-type power supply. No problem there.
I hope this helps get you started.

[sofaspud]

This kit should be just what you need.
http://www.vectronics.com/products.php?prodid=VEC-1604K