You should try this Cassandra Tutorial
after your all problem clear than another issue you can contact here & I share some information for Cassandra database related you should check this:-
I’d like to add another important thing you should know. At some point, Cassandra came with some new features, e.g. “lightweight transactions”. This sounds like a great tool at first but comes with a huge tradeoff. Think of something like “INSERT … IF NOT EXISTS” in a 100 node cluster with a quorum of 5 or so. This means your call will go round to 5 servers to check if any of them has value. This is the anti-pattern per se. Do not use this functionality! There’s SQL for such things. I don’t understand why they put time into developing this.