You should add the files, if using the neptune theme for example:
- ext-5.1.0/build/ext-all.js
- ext-5.1.0/build/ext-all-debug.js
- ext-5.1.0/build/packages/ext-theme-neptune/build/resources/ext-theme-neptune-all.css
- ext-5.1.0/build/packages/ext-theme-neptune/build/resources/images
and if using charts
- ext-5.1.0/build/packages/sencha-charts/build/sencha-charts.js
- ext-5.1.0/build/packages/sencha-charts/build/sencha-charts-debug.js
- ext-5.1.0/build/packages/sencha-charts/build/neptune/
Uploading these files you will be able to work with ExtJS the same way you did with versions 3 and 4, however, now that you updating to ExtJS 5 I would suggest you install Sencha Command and run
sencha -sdk <path to extjs 5> generate app <yourappname> <yourAppFolder>
example
sencha -sdk ../../ext-5.1.0 generate app MyApp ./MyNewApp
Move your files to the new folder making use of the MVVM structure and then running
sencha app build production
This will only add the necessary files to your final build and theme, so you won't need a bulky ext-all.js in your production app.
Good Luck with your upgrade.