How to use a side deck best?

Hey guys, so I've been making alot of decks recently, some good, some bad, some downright cheep, but I've never used a side deck, not sure how it works.

Like, when do I draw from my side deck? during the draw phrase? or when a card tells me to draw a card/summon a card from my deck? What cards are best to put in them generally?

what I was thinking, depending on how side decks work, was to have a side deck for deperate times, like fill it with protection cards such as waboku, swords of revealing light, mirror force, ect.

so basically, whats the low down on side decks, and if you've used one before how did you use it?

A Side Deck is used mainly in tournaments.

Seen as you are not allowed to swap decks, you can put 15 cards in a Side Deck and replace cards from your original deck with some in your side deck.

Side Decks are decks seperate from your Main Deck.

You go into a tourney with your 40-80 card (stick as close as you can too 40) main deck.
When you go into Round 1, you duel someone.
After someone has won the 1st game (there are 2/3 games in a match), both players go into there side deck.

The Side Deck is a 15-card deck, which contains cards to counter the deck you just played.
A player can choose 1to15 cards from their side deck, and replace them with other cards from their Main Deck.

A competative Side Deck mostly contains cards that counter the current meta. As an example, lots of people side in 2/3 Legendary Jujitsu Masters as they are good against GB's and BW's, GB's can't tag out and BW's can't run over it with Shura/Bora.

After you side deck, you go into game 2 of your match. If you lost the first round, and also lost the second one, the Match is over.
If you lost the first one, and win the second one there's another change to side deck between game 2 and game 3.

That's pretty much it, any other questions feel free to ask.

well that cleared it up nicely, thank you very much