To upgrade your current web application to latest version please follow below steps :
01. login to your account area at www.phptravels.org and download the available latest version. for example Click Here
02. once you download the latest version make sure you have installed all updates from your admin panel check below image
03. remove uploads folder from packed zip of web application
04. upload the zip package to your hosting
05. Extract your files on your root of website to replace all new files on old version
06. update database.php to connect with your existing database
That's all you are done.