You chose to bid 1 Spade. This is the correct bid. You have sufficient points and a good 5 card Spade suit.

Let us assume that the partner of the opening bidder does not bid at all.

The Reply to the Overcall bidder doesn't know the strength of his partner's hand. Because of that he is required to have more points to respond, than the partner of the opening bidder. So while the Response bidder could have got by with 6 points, you need to have 9 points to reply, and if possible you should support your partner's bid. You do know that your partner must have a 5 card suit, as that is a requirement of an overcall bid in a suit, so you can  now support him with only 3 of his suit, if you have sufficient points. The reason for this difference in number of cards for supporting comes from the idea that it is important to have eight trump cards between the two partners for a trump suit to be useful. When the opening bidder opens in a suit, he might only have 4, and that is why you need to have 4 to give a supporting bid. However, since the overcall bidder is expected to have 5, you can get the required 8 card fit with only 3 from his partner.

If you have an exceptional hand, you can bid in your own suit, but I would want you to have at least 13 points to do that and a very good suit. To go into No Trump requires 9 points but also a stopper card in the Club suit which was bid by the opposition. A STOPPER means a protected honour. Remember we said before that for an honour to be protected, it had to have the number of small cards that was required for it to lose before the honour became a winner. So if you have a King, you are required to have 1 protection card, and with a Queen, you would need 2.

Let's look at the hand below which we will say belongs to the Partner of the Overcall bidder, and see what the best bid will be.  Remember, so far the bidding has gone: 1 Club, 1 Spade, No Bid -

Spades         J,8,2
Hearts         A,Q,9
Diamonds    A,10,9,8
Clubs           8,5,2

24. What should the partner of the overcall bidder bid on this hand?

a. 1 No Trump
b. 2 Diamonds
c. 2 Spades