How do I change my all links like https://ift.tt/2K5tnMe to simple https://ift.tt/2mQOEQV

Actually I have a site but I don't know how exactly one can resolve this kind of issue.

So, my site is qapaper.com and there are some links which redirect on one single page with PHP GET methods which are:

 https://qapaper.com/first.php?id=1
 https://qapaper.com/first.php?id=2
 https://qapaper.com/first.php?id=3
 https://qapaper.com/first.php?id=4

Each having question papers of different year, now here comes the question that how can I change them to something like:

https://qapaper.com/first
https://qapaper.com/second 
https://qapaper.com/third
https://qapaper.com/fourth

And second thing is even my landing page is like:

https://qapaper.com/index.php

Thank You in advance!