xml for a dummy (me)

I took an introductory XML class several years ago which dealt in theory, not practical stuff, and am finally faced with my first xml project. A vendor requires that we send updates to their database as an xml file. Our data is SQL based. They have provided an xsd file with the requested layout of the xml file.
Now what?
We are using SQL2005, and I'm playing with Liquid XML Studio.
I also have vb6 and .net, although I'm better at vb6 than the .net...

If anyone can point me in a general direction I'd appreciate it.
Thanks
Steve