Galaxy Tab 3: How to get it to make use of the MicroSD card?
There are multiple things for you to check out:


our insufficient-memory tag-wiki gives you some general information, background, and first aid on the storage problem
our app2sd tag-wiki will let you know about moving apps to your shiny new SD card
your camera app will certainly have an option to tell it where to save new photos/videos – set that to your new card. If it does not, there are plenty of alternatives available. For some specific recommendations, see Camera software for Android on our sister site.