Identification of how the bond plot and the casket plot were introduced

The bond plot is introduced at the play's beginning. Bassanio needs money to compete as a suitor for the beautiful Portia but doesn't have it. He requests a loan from his good friend Antonio, a wealthy merchant, but Antonio doesn't have any actual money in his possession (all of his money is tied to financial ventures), so he offers to visit the usurer where he guarantees the bond with a "pound of flesh." (Act I, Scene I)

As for the casket plot, we learn about that in the second scene, as Portia confides her feelings about the marital stipulations her father has left in his will to Nerissa. She cannot choose her suitors and her eventual husband will be based on the casket he in turn chooses. (Act II, Scene II)