where can i find pages for 10.11.1

You are out of luck. Apple only keeps the most recent release of Pages, Numbers, and Keynote in the Mac App Store. There is no Apple download site for full past versions. Right now (2017-11-18), these applications require macOS Sierra 10.12+ or later for installation.

Here are your options:

1. Use the free Pages for iCloud by signing in with your Apple ID.
2. Restore Pages v5.6 or later from a Time Machine backup
3. Office 2016 for Mac
4. LibreOffice Suite (free, you want the most current (fresh) release)
5. Any other non-Apple word processing application (see Mac App Store)
6. Buy the retail iWork '09 DVD from Amazon/Ebay, and after installation, update it to the last application versions (12/2012). This will not open any Pages, Numbers, or Keynote documents created with the newer applications.

Pages ‘09 works on macOS 10.11.6 as it does on most Systems and is available from Amazon as part of iWork ‘09 quite cheaply.

Peter