1) First thing you always want to do is set your desired race and class. This is because any time you change these values all of your trait selections will be reset. Alternatively, pulling in character data will populate the race and class fields for you.
2) Select the traits as you normally would in game, all of the tabs across the top and bottom will work as they normally do. Currently, all virtues are assumed to be at rank 10.
3) As you select traits, you will be shown a build summary in the right panel. The "Raw Buffs" section is simply the aggregated bonus's of the traits you selected. The "Raw Buffs Processed into Seconary Stats" is the aggregated bonus's of the traits but processing all primary stats into secondary stats, for instance 1 vitality = 3 max morale. Any traits that grant bonus's or abilities that are not stat buffs will be displayed at the bottom.
4) When your build is complete, you can go back to the Equipped Traits tab to see your build summary. You should note the two buttons in the upper right. The figure eight will open a window with a link to this build that you can give to other people to see what you've done. The "X" will allow you to reset all your selections. Please do not refresh your browser to reset the build, as each browser may do this differently.
5) Thats it! Enjoy using the trait builder! Remember to report any bugs and request any features in the forums! Thanks!