Hey, welcome to the forum.
One of the best places to start is the Tutorials section. Browse around, find something you'd like to try, and start drawing. After that (or if you already have a drawing you'd like to share) you can upload your image to the gallery, and post it in the Critique Corner for some critique. You can also join us on the Groupboard and get feedback as you draw (you may want to use a tablet for this, but if you don't have one, a mouse or touchpad can work too).
Hope this helps. :)