If you're just starting in VB6 (like I was 1-1/2 years
ago) you'll only need two texts, BEGINNING VISUAL BASIC 6, by Peter Wright, and TEACH YOURSELF VISUAL BASIC 6, by Scott Warner. Both are available from amazon.com
a) They don't assume you know ANYTHING, yet,
b) They illustrate things with plenty of simple
examples, and
c) They have simple exercises - to let you test
things out.