Plotting 3 vectors in 2d

I have excel sheet of 3 columns data. The 1st 2 columns are x and y axis while 3rd column will be the contour type lines.

Check this steam table graph:

So I have values for pressure and enthalpy in 1st 2 columns and on that I want to plot 3rd column which is red lines in above graph. So how to do that?

[adi kul]

For more details, I have values of 3rd clomun corresponding to the 1st and 2nd columns!

[Purushottama Rao]

is the third column to be plotted as the funtion of entahlapy?

[KL]

contour plot?

[adi kul]

ummm yes you can say contour plot but I don't have any relation between these. I just have numbers. I tried scattered method, cftool but no luck!