Install Qt on Ubuntu

Need to build simple GUI application. For this reason I decided to install Qt on my Ubuntu 16. I have downloaded open source Qt edition [from theirs site][1]. Got error while run: <!-- language: none --> g@ubuntu:~/Downloads$ ./qt-unified-linux-x86-2.0.5-2-online.run ./qt-unified-linux-x86-2.0.5-2-online.run: error while loading shared libraries: libX11.so.6: cannot open shared object file: No such file or directory How to fix that? [1]: https://www.qt.io/download-qt-installer?hsCtaTracking=9f6a2170-a938-42df-a8e2-a9f0b1d6cdce%7C6cb0de4f-9bb5-4778-ab02-bfb62735f3e5