To draw a card from your deck you must have sufficient action points (usually 3 points) available and free space in you hand. The maximum cards you can have in your hand is 8 by default for all factions except the “Machine Empire” whose default is 9. This can be modified by special abilities of cards that you have in play and espionage activities conducted by enemy factions. If those two conditions are met you can draw a card by left clicking the following button on you “Card Hand” interface display.