When I create a simple program .cpp file. How can I convert it to a program or software to work on a Mac system? or even do some design for it too. I would like to open it as any software on my Mac and use it. I know that I should use Xcode, but how? I did search with no luck.
XCode is available somewhere in https://developer.apple.com/ You will need to make an apple developer account. You do not have to pay any money to download XCode or when making the account.
OP is not crystal clear to me so there are a number of possibilities:
a) As far as XCode is concerned, if you already have the cpp etc file(s) prepared under VStudio, say, then just copy them across and compile under the normal XCode way by making a new blank C++ project.
b) If you do that and are having trouble finding the executable and how to run it then this would be very much the same as recently discussed here so have a look at this message and read the whole thread if necessary.
http://www.cplusplus.com/forum/beginner/194740/#msg937081
c) If you have already prepared an exe file using VS or some other PC based system then you'll need WINE (MacPorts I'm not familiar with so have no comment) Remember that programs requiring window API are not really suitable for Mac's. wxWidgets tries to overcome this.
d) Don't forget there are other alternatives to XCode eg Qt creator which is equally good doing the same as Xcode. (Qt Creator is a slow download but good)