I am confused that, where to start? I want to send feedback from my phone to generate jira ticket, but thae problem is- Unable to find how to create base url to send data to jira server.
In that case, the base URL should be https://<your-company-name>.atlassian.net or something like that, basically the URL you browse to when you need Jira.
Perfect, Now second thing-
I want to post some data to Jira cloud to create ticket, What the json format of it ?
have no experience with that part, but you can find a lot of information n https://community.developer.atlassian.com/t/create-issue-in-jira-cloud-using-rest-api/2774 and feel free to read the developers guide for the REST API of Jira Cloud.