You’ve probably typed Shift-S which drops a 2D image of the model to the canvas. To clear the canvas type Ctrl-N and drag you’re model again if you have to. Also recommend watching any of the Intro to Zbrush videos of Michael Pavlovich. Zbrush for Ideation
For the fingers, either increase the Dynamesh resolution or, better still, spread the fingers apart if you want to keep the mesh density lower at the beginning of your sculpt. To remove the mesh between the fingers, one method would be to use drag lasso, select the mesh between, invert the visbility (Ctrl-Shift drag), and delete hidden (Geometry: Modify Topology:Delete Hidden). Then move the fingers apart before running Dynamesh again. Dynamesh will close the holes that were made after deleting the mesh between the fingers.