giorgosvintzi,
Welcome to the API testing world and amazing to see your enthusiasm to learn new things and experiment.
And you are successfully get started with ease.
This readyapi is tool is not only to be able to test our API's, but also test the flows & and automate them.
You should be able find various online resources & videos etc.
Here are some:
https://support.smartbear.com/readyapi/soapui-pro/videos/But you can also find in youtube.
Here is documentation link:
https://support.smartbear.com/readyapi/docs/index.htmlIs it that you need to test some webpages too as part of tests? then you need to do little more search online.
Anyways, if you have any specific issue feel free to post in the respective forum.
Good luck.