To actually answer your question Massie.
You get new skills by solving cases.
As you solve each case you earn Experience Points. You will earn a new Skill point every so often along the way. In the beginning you will earn skill points quickly, as you get more experienced they come slower (require more experience points to earn 1 skill point).
Choose your skills carefully, read over several of the threads here in the Newbie section and in the Moderator's picks for ideas.
Of course ask questions also.