Hi, wish everything goes well with you

response surface models in design expert such as central composite design and box behnken are mostly used for process optimization. Working with the software is not complicated. All the things that you should do is to design your experimental chart with your desirable algorithm (CCD, box behnken...) once you have done your experiments according to the chart and entered the results into the software as the values of your responce variables, first you analyze your datas by clicking on ((analysis)) and choose a model for your responce variables in order to the ANOVA analysis to be done. after analyzing the data, you can go to optimization tab and select the range of your input variables and determine the goal for your response variables (minimize, maximize, special target...) and then 

http://www.statease.com/software/dx10-tut.html

do you know about center point i can't understand this point