How would I go about drawing in a paint program with pressure sensitivity?

How would I go about drawing in a paint program with pressure sensitivity?

References

Reference NO 1

http://stackoverflow.com/questions/15165591/how-would-i-go-about-drawing-in-a-paint-program-with-pressure-sensitivity

Reference NO 2

http://iridogorgia.deviantart.com/journal/Pressure-Sensitivity-in-Paint-Tool-SAI-230905902

Reference NO 3

http://forums.getpaint.net/index.php?/topic/13516-pressure-sensitive-drawing-not-working/

Reference NO 4

http://www.gamecareerguide.com/forums/showthread.php?t=5912

Reference NO 5

http://mac.appstorm.net/roundups/graphics-roundups/15-apps-to-use-with-that-shiny-graphics-tablet/

Reference NO 6

http://forums.lenovo.com/t5/X-Series-Tablet-ThinkPad-Laptops/Helix-Digital-Pen-Pressure-Sensitivity-issue/td-p/1092963

Reference NO 7

http://forum.deviantart.com/art/digital/1665596/

Reference NO 8

http://forum.tabletpcreview.com/samsung/47422-how-set-up-your-samsung-series-7-slate-serious-photoshop-work.html