Border Terriers have a tough wiry outercoat to protect them from the elements, and a soft undercoat to keep them warm. BTs should be stripped, not clipped, to preserve their weather-resistant coat.
An excellent tutorial on grooming the border terrier can be found on the BTCA website.
Grooming tools can be purchased at dog shows, or off of the web. There are some excellent videos out there on grooming.
And of course, there are excellent groomers out there if you don’t want to do it yourself: