I have a Rosstech vagcom lead which i have purchased s/h,does anyone know if i just follow the following link to register the lead with Ross-tech.

Ross-Tech: VAG-COM: Downloads: Current Release and Manual

If it is the official one I'd imagine so yes

From Ross-Tech's FAQs:

3.10 Can I sell my VAG-COM System to someone else?

You can sell the Interface, but the software license and support are not transferable.

If you have a "dumb" interface and the purchaser wants the full-function version, he will have to register as a new user for $99.

All of our Current Interfaces act as "dongles" for VAG-COM, so the software should be fully functional on any PC that meets our requirements. However, we only provide support to the original purchaser. If you purchase a second-hand "dongle" Interface and want to be a "registered user" and get technical support, you'll still need to pay $99 to register. 2nd hand owners of Ross-Tech Interfaces are not eligible for any of our Trade-In offers.

Ok may be a dumb question?

What do they mean by support?

Yes it is a genuine lead.

What do they mean by support?

What we mean by support is that those that buy product direct from us get full support for the product and also get support with repair information for their specific car whenever possible. Our tech support staff answers phone calls and answers emails.

Are we masters of repair? No. We simply have accumulated a vast amount of information that we are releasing to the public over time and we do attempt to give the user as much assistance as we can.