When you create a Hero in Advanced HeroQuest, the first step is to determine what race
your character will be. This process is described on page 43 of the basic rulesbook.
However, the house rules and additional race options listed on this site significantly
expand and modify your options. For convenience, these rules are summarized below,
with the new races included.
Once you know the Hero's race, you can roll his characteristics. These are the figures that determine how good or bad a fighter he is, what chance he has of casting certain spells or using certain skills, and so forth.
To create these characteristics, the table below indicates that you should roll a die and add a number to the resultant score. For example a "D6 + 4" means that you should roll a six-sided die and add 4 to the result, which will give you a random number from 5 to 10.
You can either use the appropriate dice (e.g., a six-sided die for D6, an eight-sided die for D8), or else the twelve-sided die included with the game can suffice for these numbers. Simply roll the die, and discard any values higher than the maximum. For example, to simulate a D8, you can roll the twelve-sided die and reroll scores of 9 to 12.
Another method is to take a die and to divide whatever value you roll by the appropriate factor, rounding all fractions up to the next whole value. For example, to simulate a D3, you could roll a twelve-sided die and divide the result by 4, or roll an ordinary six-sided die and divide the result by 2. (On a twelve-sided die, 1-4 would give you 1, 5-8 would give you 2, 9-12 would give you 3.)
For each characteristic, roll the die shown in the column for the Hero's race.
There are also certain special character types you can choose (the Wardancer and the Trollslayer) that come with pregenerated statistics. In that case, you do not roll randomly for your statistics. Simply copy the statistics for the Wardancer or the Trollslayer, as found in the Terror in the Dark supplement.
With the GM's permission, you can play a few more exotic race types, such as a Half-Elf, but in this case, simply choose an existing race that comes close to what you have in mind, and use the rules and statistics for that race. (In other words, your Half-Elf may have a mustache and pointy ears, but ultimately in game terms, he's treated as a Human or as an Elf.)
More details about the differences between Elves are given here.