how to plot coordinates on a contour map

I have a contour map with 20 contours of a 32x32 matrix called map_matrix.

I need to plot the locations of 3 treasures, their coordinates are in another matrix (3x2) called "treasures" that was obtained from map_matrix, that contains on the first column the y coordinates and on the second column the x coordinates.

I got the contour map,

Using an X marker I was asked to plot the treasures locations using a marker size of 15, a line width of 4 and a red color.