How to install php 7.x

totally new to linux stuff, i have done all i can from scanning the web and having my vps working . sadly the php switcher is not working and i need to switch php to higher then current version to upgrade my magento 2 .. so how can i install php 7.x and what should i do after has been installed
Tanks

before posting for help, i did all i could from cwp .. however, i decided to use php selector setting .. i click on install dependencies once this was done , went back to php selector and selected the version7.24 and compiled , and to my surprised .. it did switch to this version and testing on client side with script verified it ..