You need to supply some more detail with this question. What type of graph? What does the data look like? Are you using menu drive JMP or scripting via the JMP scripting language (JSL)?
I am Using JSL. see the code below i am using to create XY plot.
1. Now i want to change the legends which appears right vertically to Top of the graph and horizontally.
2. i want to add add some kind of (say median of column summarized by legends
dt = Open("$SAMPLE_DATA/Pogo Jumps.JMP");
biv=Bivariate( Y( :Total ), X( :Yat ));
report(biv)[frame box(1)]<<frame size(400,300);
report(biv)[Framebox(1)]<<Row Legend( Finalist,
Color( 1 ), Title Position ("Top"),
Color Theme( "JMP Dark" ),Marker( 0 ), Marker Theme( "" ),
Continuous Scale( 0 ),Reverse Scale( 0 ),Excluded Rows( 0 )