also what do the boot things mean on the card, for instance eriksen has an orange one
It means he is in the wrong position.
The red/orange box thing with dots in it, indicates whether that player is in the right formation. If you look at the player details, it should tell you what formation that player should be in. If its red, it means that your player wont stick to formation in game. If its orange, it means he will, but still wander out of formation occaisionally.
The boot indicates the player's role. For example, you have Eriksen in a CF position on your team, but at the top of his card it says he is a CAM. When its red, it means he shouldnt be in that position. Kinda like having a defender as a striker. When its orange, it means he is in the right section (In Eriksen's case, in the midfield), but still in the wrong position.
what are all the contract cards for?
As for contracts, everytime you play a match with your team, each player uses one contract. If you look at your players details, it should tell you how many contracts that player has left before you need to use a contract card.
The contract cards themselves add multiple contracts to a player. For example, a normal gold contract card will add +13 contracts to any player, meaning a player can now play 13 matches.