This has been covered in detail in previous posts.
If you're having trouble finding the weather location id, go to this link ---> National and Local Weather Forecast, Radar, Map and Report
---> and find your city from the search tool. If you do a search for Boston, for example, in the address bar you'll see a code that looks like: USMA0046
Use the code you get from your search as your location id. I've found that this works for cities (Boston, NYC, LA) but not so much for towns (suburbs). You may need to choose the city closest to you in order to get a proper code.
There are other ways to find the location id, but this works best for me.