how do I save a pdf and where does it go on my computer?

Ironically, 11 megabytes really isn't that big these days! 

Acrobat Pro has a Save as Optimized PDF function that provides options by which you can generate a new PDF file with reduced image resolution and/or image quality as well as some other tweaks (such as metadata removal) that may help reduce the PDF file size.

However, at some point, you get to a point where either there is either no further size reduction possible or the resultant quality is too poor. Ultimately, you cannot legislate the size of a PDF file. Content takes space. You didn't say how many pages and what those pages contain to take 11MB. But for example, if you have a 20 page PDF file with high quality, high resolution raster graphics on all pages and the e-mail recipient expects to be able to print that document, that 11MB might be the most compact file size that you reasonably send and still meet expectations.

          - Dov

PS:     Not a good idea to post your e-mail and phone number on these forums if you expect not to receive undesired e-mail messages and phone calls from unscrupulous internet lurkers.