If all has gone well you should see webCoRE listed under a ‘Custom’ subheading as an available SmartApp. So that means you should be able to hit ‘+’ on the Favourites or Automations tab, choose ‘Add SmartApp’, scroll down, and find webCoRE waiting for you.
If you don’t see it listed you might want to compare your installation process with the instructions on https://wiki.webcore.co/ to make sure the bit up to installation in the app is correct. The usual ‘gotcha’ in older instructions and videos is to have you install on https://graph.api.smartthings.com/ rather than the actual servers you need to be on.
As for whether it is a good idea to be installing webCoRE … Just be aware that webCoRE is a legacy app and the obstacles to SmartThings turning off the legacy platform are gradually being eliminated. Also you may find increasing numbers of things that aren’t back compatible with the legacy platform. Unfortunately one thing SmartThings are particularly good at is keeping things under their hats.