This instructable will show you the basic survival skills to get past your first day in Minecraft.
Henceforth, "Harvest" means left click and hold until said block has dissapeared and you are able to collect it, and "Place" means to right click in said place with said block weilded. Also henceforth, if "Realtime" is not in front of "Day" it means that the day in an in game day. If "Realtime" is in front of "day", it means an actual 24-hour day.
To henceforth again, henceforth, a "Mob" is anything that has the ability to move between and across blocks without the player touching, or adding anything to it. (E.G. sheep, ducks, spiders, zombies)
All of this is advice and how-to's for a beginner player in Minecraft. You should advance and do more daring things once you are comfortable with these skills. That should not take too long, if you play regularly.
Step 1: Punch that wood! (or dirt)
Your going to need a shelter and some light sources. What do you do? Get some tools! (or dirt) You can make tools by harvesting the tree logs. Once you have about 5 logs, press "i", and make some planks (http://www.minecraftwiki.net/wiki/Crafting This gives you information on how to make whatever you can make, what you need for them, and many other facts about the item.) After you make the planks, make a wood pickaxe.
Now you need to find some coal. Normally it is quite easy to find. It looks like a normal stone block with black speck in it. Mine/Harvest it, and collect the coal. Then, make a torch (again, please refer to the crafting link I shared above.)
Now you can harvest anything you can see and make it into a house. The building of the basic house is self explanitory.
At first, it will probably be just a small cube, then you will want to expand it, or build elsewhere. You get to pick where you want to be. You could be underwater, which would be a huge hassle on the first day. You could be on a plain, which would be very good for a beginner, or you could be underground or in/on a cliff. The last is my favorite, but making it look good is hard sometimes.