
Step 1: If you are on a Windows PC, go to apple.com and download the Safari browser. Mac users already have Safari on their system.
Step 2: Once you install Safari, go to Edit -> Preferences -> Advanced and check the option that says "Show Develop menu in menu bar."
Step 3: Open the "Develop" option in the browser menu bar and choose Mobile Safari 1.1.3 - iPhone as the User Agent.

Step 4: You’re all set. Open zinio.com/iphone inside Safari browser and start reading your favorite magazines for free. Use the navigation arrows at the top to turn pages.
No Safari download required.
In Firefox: enter “about:config” in the location bar, enter “useragent” in the filter and change the value for “general.useragent.extra.firefox” to “Mobile Safari 1.1.3″.
After reading, set it back to “Firefox/2.0.0.14″.