Use Wso2 Enterprise Integrator where You can create API and Apply the various integration patterns to achieve your requirement. Then if you need you can publish the same in API management.
ESB requirement:
You can use either a management console for creating API's or an eclipse designer extension from wso2. For creating API's XML knowledge is enough otherwise it also provides drag and drop feature.You don't require JAVA knowledge as the inbuilt mediators which are shipped with Wso2 ESB is enough. But if you have knowledge of java then you can create custom meditaors(mediators are used for creating busniess logic
) incase of some special needs. If you don't know JAVA then you can use Javascript, Ruby, Groovy inside script mediator. I prefer for smaller transformation I will use Script mediator if you have larger message size then you can go with class mediator that's where we'll use JAVA. This is all the requirement you need for ESB.
Technologies required for ESB: XML, XPATH, JsonPath, XSLT, Xquery , scripting knowledge(Javascript, Ruby, Groovy
)etc.
If you are beginner then please refer this tutorial https://docs.wso2.com/display/EI640/Integration+Tutorials
For API management programming knowledge not required.