Sometimes the questions that we think of are simple and so are the answers. But we don't know them. Here are two common questions and their answers.

Question: How do you move something, like Documents, into the bar at the bottom of the screen with the other icons?  

Answer: The Dock at the bottom of the screen is divided into two sections, one for Applications and the other for documents / folders.  It is split by the dotted grey line near the right end that kind of looks like the paint on a highway. You can add Applications (like Word, Excel, iPhoto) to the Dock by dragging them to the left side of that grey-ish line.  To add folders or specific document(s) to the Dock, drag the item to the right side of the line.  

Question: Why does the mouse controlled arrow frequently and suddenly dart to the far side of the screen without any movement on my part?

Answer: The mouse is probably jumping due to the kind if mouse pad you use.  The changes in the image are confusing the laser and causing the jump.  As a test, try replacing the mouse pad with a colored piece of paper, preferably dark and the behavior should stop.  If it does, try a new mouse pad.