There are ability vendors next to a number of the hardlines in Richland, the first most people find being in Uriah.  Once you purchase the abilities, you can just load them up at any hardline (or in the loading area) and level whichever need levelling. 

Once you reach level 10, however, you'll have to travel outside of Richland to buy the abilties you'll need.  Eventually you'll reach a point where you can't buy the abilities at all and must craft them (or have a friend craft them for you).

Weapons decay with use (some decay VERY quickly) and clothing items decay randomly by you taking damage.

You can repair "broken" items using a repair tool and the appropriate skills in the crafting tree as long as there are small dots remaining for the item (if you hover over an item's icon, you can see it's decay status).  Once an item has decayed completely, however, it's still not completely lost as you can then try to decompile it (once again, using the right tool and the right skills in the crafting tree).  If you suceed in decompiling the item, you can craft a new copy of it using the code bits and fragments you've probably already noticed yourself picking up.

Collector's items, construct drops, and other special items, however, can't be decompiled after they have completely decayed and have to be collected again.

I have read over the newbie training stuff but I didn't see, or missed it, where to go to start working on the different trees.  I got to lvl 6 but all I have been able to do is lvl up my awakened skill set.  Definitely need some help here.  Thanks.