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What are you trying to say?  Your last two posts here have both presumed that we all know what is going through your brain. If you want to make a point, or if you want help, you need to explain better.

You are an engineering student, correct? Communication is an essential skill for an engineer of any discipline. You will not get far in engineering until you learn to communicate clearly and effectively.

i did not understand what you mean as I always asked in order to understand perfectly even when I had small doubts. well Im running the arduino by using an AC-DC adapter.now I bought this Xbee http://www.adafruit.com/products/126 which states that 3.3V regulator on board. on forums I found that people had problems and that its better to add a voltage divider by using resistor or even a 3.3v voltage regulator chip in order to safeguard the xbee. when i was reading on this page, i found this:

'The wire link between the xbee and the arduino has 4 wires: 5V, GND, DATA1, DATA2.' 

​now I want to ask, the 5V maked on Xbee should it be connected to the 5V pin on the arduino or can I cannect it to 3.3v on the arduino?

​I'm sorry if in some way or another I disobeyed the rules of this page

No, you did not disobey any rules, you did not give me (or anyone else) enough information to know what your problem was. You have now given me almost all the information I need. If you had written this the first time, I could have answered you sooner.

You can run the Arduino at either 5 V or 3.3 V. If you are running the Aduino at 3.3 V, then you can feed the xbee with the same 3.3 V and you do not need the adapter kit. But you can use it if you wish. Look at this page http://www.ladyada.net/make/xbee/ about the Adapter Kit near the bottom and you see a picture with the connections marked. I read that as meaning you can feed 3.3 V on the pin marked "3 V from regulator (or input)".

If you are running the Aduino at 5 V, then look at the page again:  you can EITHER feed 5 V on the pin marked "5 V - Power to regulator",  OR you can feed 3.3 V on the pin marked "3 V from regulator (or input)". But you do need the Adapter Kit for the input signals. Under the picture it says "The DTR, RTS, RESET and RX pins (going into the XBee) pass through a level converter chip that brings the levels to 3.3V."  That means you can safely put signals from the Arduino that switch between 0 and 5 V onto these pins.

To find out whether the output from the xbee can be recognised by the Arduino input, you need to look at Table 28.2 of the Atmel Data Sheet. That tells me that if the HIGH voltage (V_IH - Input High Voltage, except XTAL1 and RESET pins) is greater than 0.7 V then it will be recognised (and the LOW voltage needs to fall below 0.3 V to be recognised - see the line above). It is almost certain that the xbee will output a voltage higher than 0.7 V for a logic HIGH (but you could check in the same way) with the xbee data sheet.