Why won't my Minecraft automatically update and how do I update it?

I seem to be eternally stuck on 1.7.4… I got Minecraft for Christmas and it hasn't auto updated since so if anyone knows how I can get it to update that would be great!

On the launcher, click "Edit profile", click Use version: then select "Use Latest Version". If this doesn't work, you may have to re-instal Minecraft. If that does happen to be the case, make sure you save your "saves" folder, it saves your single player world data. If you're using windows, you can access it by clicking Start, typing in %appdata% and selecting the.minecraft folder. Hope this helps!

Can you give us more info?