FAQ/New Skills
For all classes, to learn new skills, and upgrade existing ones, you need to talk to your class trainer.
You'll find at least one in every city - they are named "[classname] [name]" - so look for "Venomancer (Hu, I think it is)" and you'll be looking for "Wizard (someone or other)"
You can also hit the little green arrow next to the minimap and see the list of nearby NPCs and double click to get an autoroute to them.
Talk to this NPC, and you will get you a menu of skills available to you.
Then you need to be high enough level, have enough coin and spirit, have done the appropriate quest (for some skills) have fulfilled the requisites (most skills need a single level of the skill before them in the tree, some have more) and the skill will be lit up bright in that list.
Click it, and you've got it. Once you're done on that screen, hit 'r' to get your list of skills and drag the ones you like to your hotbar.