"Do something broken or get beaten by the people doing something broken." -- Ari Lax

First, some basic theory behind Storm. Your deck is implicitly divided into 4 categories: mana, draw, disruption, and business. The optimal maindeck ratios for these categories boils down to something like:

30 - 32 mana sources (lands, artifacts, rituals)
12 - 16 draw spells (cantrips, etc.)
6 - 7 disruption spells (discard, removal)
7 - 9 business spells (tutors and win conditions)

My version listed here runs a ratio of 31:14:6:9. This can be broken down even further along categories defined by Jon Alexander's article "The Storm Box": https://theweeklywars.wordpress.com/2015/04/29/the-storm-box/

Lands
Fast Mana (Bulk)
Fast Mana (Initial)
Interaction - Hand, Stack, Battlefield, Graveyard
Soft Business - Cantrips, Pseudo-Engines
Hard Business - Tutors, Engines, Payoff

Sideboarding wants to maintain these elements and adjust the ratios accordingly for each matchup. For more info on this, you should read Carsten Kotter's article: http://www.starcitygames.com/article/29060_Stormboarding.html