The first, and most important part of your build that you’ll have access to are your weapon skills. When you create a new character, you will have a main hand weapon equipped, with the first skill automatically unlocked. As you actively engage in combat and defeat enemies, you will progressively unlock the remaining skills for that weapon.
For example, new necromancers will be able to activate the Death Shroud mechanic [F1] once you’ve built up enough Life Force. This gives you temporary access to 4 unique skills, though only the first of these (Life Blast) will be unlocked initially. As you continue using Death Shroud actively in combat and defeating enemies, you will progressively unlock the 3 remaining skills.
All professions have access to 3 unique healing skills, with an additional healing skill available based on the race of your character (Human and Sylvari only). Once an additional healing skill has been purchased, you can slot it on your hotbar by clicking on the small arrow for that skill slot. A full list of skills available for that slot will appear, with locked skills being grayed out on the list.
The second part of your build that will automatically be unlocked (either partially or in full depending on your profession) when you begin the game is a unique mechanic specific to your profession. In some cases these profession mechanics will also need to be progressively unlocked through active use, similar to your weapon skills.
You will need to complete this unlock process for each weapon your profession is able to equip. To see a full list of available weapons for your profession and a list of the associated skills, open the Hero window [H] and on the left side open the Skills and Traits tab (shown above to the right).