What exactly you mean by "Cloud computing" here. I guess https://cloud.oracle.com/tryit provides cloud access to Oracle Database.
However if you want to learn Cloud or Virtualization (how to implement Cloud infra) you could probably research on some Virtualization tools. Popular ones are VMware vSphere, Citrix Xenserver, Microsoft HyperV, Oracle VM Server etc
Oracle VM Server provides lots of templates (virtual appliances) ready for use (Just download and use).
You can read more here: Oracle VM Server for x86 | Virtualization | Oracle
And we could probably discuss this over the OTN Virtualization board https://community.oracle.com/community/developer/english/server_%26_storage_systems/virtualization/oracle_vm_server_for_…
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