To janab_a
You must be running an old version of .NET because System.IO.Ports is available in .NET 2.0. You can easily upgrade for free.
Added after 53 minutes:
To zeamadoo,
I don't think anyone has addressed the last part of your question, so I'll try to help. I assume that you have decided how to collect the data into your application and now you want to communication it over the internet to your website. It would help to know how you want to use this data since there are many approaches.
At the lowest level you will be using a TCP/IP connection to talk to your website. You can implement this at the lowest level using TCP/IP functions (a huge amount of work), building your own communication classes (lots of work), or you can take advantage of the pre-built classes available (both free and fee) or you can use the high level System.Net functions built into .NET, just to mention a few. You can also buy turn-key servers that plug directly into the network if you want to save a lot time and the cost is bearable.
So you need to make some decisions about the architecture, cost and schedule for the entire system and how you want it to work before choosing an implementation.
If you've never done this before, be prepared to spend some time getting it all running. Don't forget that the client side needs to be implemented also.
Hope this helps.