The latest Fire of mine has a microSD slot (up to 128GB which is great for your personal content and downloading movies, music, books, etc. If you just bought it, then return it and get the better one. Save up if you have to but purchasing one with at least a 32GB internal HD is best for long-term use. Of course, Amazon is NOT going to give good deals with the higher HD options. At minimum, you should shoot for 32 or 64. The OS 's future updates must fit on that HD. Nowadays 8GB is nowhere near large enough.
2012 HD, HDX 8.9' (the best out of the 3 and overall from my experience) and 2016 Fire.