CodeSign错误：SDK'iOS 6.0'中的产品类型'Application'需要代码签名

I have dowloaded a project name called Plot_Gallery _ios which is mainly runs for plotting of graph.This was downloaded from core_plot,the main target project is Plot_Gallery_IOS and also it has sub project file called CorePlot-CocoaTouch.xcodeProj whic contain all library files which is mainly used of running of this project.I have dowloaded a project name called Plot_Gal