Dear Feng

From the sdm application, you click on the combine image button. First you select the number of images you want to combine (lower and upper separately) and the assumed correlation (you can leave the deafult value or you can set a higher one). Then, you select the maps you want to combinen (all the path will be directly set fron the folder button), and after you will choose the name of the new image. Note that the combine image with the var file will be saved in the folder of the meta-analysis, so you will have to move it into the pp folder for further analysis. You will also have to change the name of the studies in the sdm_table (e.g. you combine analysis_A1.upper with analyisis_A2.upper = analysis_A.upper, you will have to remove analysis_A1 and analysis_A2 from the sdm table (once you conducted the preprocessing) and set analysis_A.

Kind regards, 
Lydia