Viewing Google Earth in offline mode I have a tablet (Android 4.1) which does not have 3G internet. I have installed Google Earth and I heard that there is a solution for viewing maps offline.

How do I do that?
As of current writing, Google Earth doesn't support full offline mode, in which you can specify to download certain location's satellite imagery in detail. However, just like Google Maps, you can cache a small portion of it for offline viewing.
Quoting Google Earth product support,

Google Earth works best with a live internet connection. You can, however, cache (save) small amounts of data that you can access when you're offline.
To do so, log on to the internet and visit the imagery you'd like to view while you're offline. Please pay attention to the Streaming indicator, which appears just below and a little to the right of your images. When this indicator has reached 100% for the imagery you're viewing, Google Earth has gathered all available data for that specific altitude and settings, so you can disconnect from the internet.
Please remember that once you're disconnected, you'll be able to view cached areas only.

Note: there's no streaming indicator in Google Earth app. Instead, you can wait until the images are fully loaded.