Hi there, and welcome to the world of Minecraft. HighLife here, doing everything I can to ensure that you don't die a gruesome death. Before we get to that, though, I suppose I should make sure you know how to walk around and such.
Minecraft uses the standard “WASD” control scheme: “W” to walk forward, “S” to back up, “A” & “D” to sidestep left and right, respectively. You can also jump using the space bar and crouch using left shift. The mouse is used to look around and perform most actions. As a general rule, holding the left mouse button destroys objects while clicking the right mouse button places or uses objects. The scroll wheel can also be used to switch between items on the inventory hot bar (more on that soon).