Spawning in Minecraft can sometimes be a little overwhelming considering you start out with no items or buildings at all. There are a few things you should accomplish first before doing anything else when you start the game. The main objective is to create a shelter before the night starts. This is because when the night starts mobs will spawn and attack you if you are not closed off from them.
So the first thing a player needs to do is find where you would like to place this shelter. Being higher in the mountain is always a good idea because less monsters seem to spawn at higher altitudes. Another suggestion would be near Water. Water is a great place because most mobs will not spawn in it.
Once you have found the location you have a few options depending on the time of day. Look where the sun is located at and see if it looks to be setting soon, if it is then you will need to build a shelter as quick as possible. To build a really quick one just right click and dig up Dirt from the ground around you. You do not have any tools yet to mine Wood or Ore quickly so it is best to just use dirt. Once you have about 25 pieces(you can have less if you use a hill or some other object as part of the shelter. You will then need to create at least a 3x3x3 grid so you are able to fit inside the Dirt wall and close it off completely from the inside. Close off the wall and wait until daytime when the mobs stop spawning. When the sun has fully risen the mobs will start to be set on fire except for creepers and spiders. Spiders will not attack you during the day if you do not attack them. Creepers on the other hand will so its best if you exit your shelter from the top. The reason for this is to see if any mobs are located around your shelter. They will disappear on their own if they are not close to you, but if they are close then you will need to run away to have it disappear. Once it is daytime it is time to start collecting other materials and Crafting.