http://www.paforge.com/submissions/fallout/fallout_pnp_2_0.pdfIn this .pdf you will find the rules for character creation, combat, items and skill checks.
It is not expected that you will master and remember all the rules over night, but try to do your best: since it means less work for the GM(s).
As you've probably noticed after reading the book, unlike many other forum roleplaying systems, combat is divided into turns and uses actual dice to determine whether or not your character succeeds. The dice roller function is located just below the area where you put your post.
For example: If you shoot your combat shotgun loaded with buckshot ammo at a raider, then you would add a d% to see if you hit and the appropriate dice for damage, in this case a 1d10.
This way if you hit, your damage has already rolled instead of you having to roll again if you hit.
Afterwards you will also have to see if you rolled a critical, in which case you will have to roll again to see what type of critical it was.
You also use d% for your skill checks.
When creating your character, it is allowed to be any of the races mentioned in the book. However you still need to post your character, your background and your 'wish list' for equipment in the application bit.
It is expected that your background has more then just 'he is this guy'. After all the background should reveal the life your character lived before now. However keep it realistic, since a level 1 isn't very likely to have saved several towns and beaten the Enclave single handedly.
Also keep your equipment modest, you don't get to start with the best weapons and armor. After all, you are still level 1 and need to earn your equipment. Look at approved characters equipment for guidelines.
If you have any questions to the rules, then feel free to ask.