wireles access point

Hi, i am trying to set up a wireless connection to an outdoor office. can somebody confirm my thoughts on how to set up the device and or tell me how it should be set up. i want the office wifi to be on same SSID to make things simpler. the equipment i have is basic home router inside house...

I read the Do's and Don'ts sticky and I think I am providing the information that is pertinent to my question. xFinity (Comcast) is my ISP. I lease the modem/router/gateway from them. Router info: Model:CGM4140COM, Vendor:Technicolor, Hardware Revision:2.2. The input to the router is connected...