Thank you for your Help.
One way to connect to web services is to use the Codeplex project SPServices which is (free to use and) entirely client side.
SPServices is a jQuery library which abstracts SharePoint's Web Services and makes them easier to use. It also includes functions which use the various Web Service operations to provide more useful (and cool) capabilities. It works entirely client side and requires no server install.
for a backend (c#) you can if you need it. Its on msdn:
"Creating an Interface", "Creating a Provider Web Part" and "Creating a Consumer Web Part"
the most important part is "ConnectionProviderAttribute Class" as its used in the provider and consumer class. Below is a more in-depth info on the class with another example.