staying at joy city hotel and apt. in north st. of xidan in Beijing. quick and safe way to thr great wall please

As for your case, I recommend Badaling Section to you. Walk from your hotel to Xidan Metro Station to take local subway line 4 to Xizhimen. Get out from exit A1 to walk to Beijing North Train Station, where there are direct trains to Badaling section. This way shall be quite efficient and safe!