How do I reset/restore my late 2011 MBA to factory settings??

Ok, so I love my MacBook Air that I got for christmas 2011. But the thing is, I have never been great about emails. TOO MUCH JUNK EMAIL!!! Also the whole photostream thing, is kinda overwhelming me because its SUPER hard to delete them off of iPhoto. And then theres the fact that the category "other" takes up 25 GB of space!! So my idea on how to fix that and try and get a better start with iCloud on my iphone 3gs (because I have it for another year) and my iPad (1st generation), I was thinking I would reset/restore (i honestly dont see a difference between the two) my MBA to factory settings as if it was brand new and get a fresh new start on that and my phone. Because on the phone (and iPad), Apple makes it so easy to just go to settings -> general -> reset and boom-boom-boom you're done. Now, I dont think that my MBA came with a flash drive or OS disk. And I dont know how to do all the complicated code entering or whatever. I live in an area where there isnt really an apple store nearby so I dont think taking it in to them will work either. But I've already backed all my stuff up to 2 flash drives and all my contacts are hand-written down in a contact book. So, is there a way I could just basically get a new start on the MBA? Thanks and sorry there are so many "can'ts" and "i dont understands". I am 14 and pretty good with computers but this is my first Mac so I'm still trying to learn it! But, thank you in advance to all those that try to help!!

~Appgirl2020