Magento 2.2.3 upgrade

please I made a test site to try to upgrade my Magento 2.2.3, but until now I haven’t succeeded at all. I could understand if I have to stop at 2.2 or go directly to 2.3, and if possible how to proceed too. I can not understand and I can not find info, thank you very much.

for example, if I had to step by step which version do I go to? do i change the php version first?