Even if you do nothing, in a week or two, you'll get a letter from HGVC with a membership card, followed by its bible, the "Members Guide." You'll also get a welcome kit from HHonors with a "silver" membership card.
If you have another HH account #, the two can be combined into one. You may also want to sign up for an affiliated CC from Am-Ex or Visa to boost your HH-point totals.
BTW, the Members Guide is required reading. It could easily take you 3 or 4 times thru, b4 you can pass the test. But you'll find lots of nifty pictures to make you think, "Damn, I should'a bought more points!"