Bridge guide for experienced Spades player?
The two games have some similarities. But they have a lot of differences too. Spades is a lot simpler, and so going from Bridge to Spades is relatively easy. Going from Spades to Bridge, well you're slightly ahead of the curve in having played a trick-based partnership game, but there is still a lot of other stuff to learn.
To be honest, any general introduction to Bridge would work for you. The bidding in Bridge bears absolutely no relation to bidding in Spades - this is the part you'll need to learn (and hence the section of the guide you want to pay attention to) - there are a lot of conventions to learn. The gameplay is relatively similar in Bridge, but a) there is a dummy hand which is controlled by his partner (declarer), and everyone can see it; and b) players know a lot more about other people's hands because the auction/bidding has a lot more detail than in Spades.