Add Custom Permission to Group

thanks dost

http://www.c-sharpcorner.com/UploadFile/54db21/set-group-permission-to-list-in-sharepoint-2010-programmatic/ 


This should work for You ..

 SPWeb web = SPContext.Current.Web;

                SPGroup group = web.SiteGroups["Group Name"];

                

SPRoleDefinition rDefination = web.RoleDefinitions.GetByType(SPRoleType.Reader);

                SPRoleAssignment rAssignment = new SPRoleAssignment(group);

                rAssignment.RoleDefinitionBindings.Add(rDefination);