You chose to bid 2 Spades. This is the correct bid You have 3 Spades, which is enough to support an overcall bid in Spades, and you have sufficient points (11) to give a bid.
Now the bidding returns to the opening bidder. However, since his partner did not bid, he would have to have an extremely good hand to carry on with the bidding on his own, so he will No Bid.
Your partner now needs to decide whether it is worthwhile going any higher. If you cannot make a game bid, there is no point in bidding higher. You know that the opening bidder has about 13 points. You know your partner has at least 9. Adding his 9 to your 15 makes 24, which is not enough points to be confident of making a game bid of 4 Spades. You might well make 3 Spades, but it is better to leave the bidding at the 2 level, and if you make an overtrick, fine and good. So you No Bid.
There then will be No Bids from the other 2 players, and the bidding has finished. West has to play the contract of 2 Spades because he bid the Spades first.
North makes the opening lead. Here is his hand. It is no wonder that he did not bid.
25. What should the opening lead be?
a. 10 of Clubs
b. 2 of Diamonds
c. 6 of Clubs