Click on

Build your draft

Select the set and click then choose the booster type and the qty of boosters

you can mix sets and booster's type.

then click to crack your boosters ;)

pick your cards, make your deck

To help you, you can sort your draft by cmc, color, type or rarity.

Drag your selected card to the right

you can complete your deck with basic land :

click to store your deck