I am able to do a transation in my private nework using geth console.
But I want to the transaction on a dapp without using any wallet
You should use Web3. Then you can do access a node and do transactions from your own website. You can also use web3 for python.
When you say without a wallet what do you mean? A Dapp will use Web3, most popular is the web3.js library. It lets you make JSON-RPC calls to your node.
To get started: https://github.com/ethereum/web3.js/
There are other libraries as well use as the web3.j for Java, Nethereum for C# web3.py for Python. Implementing on web3.js has a lot more community support and tutorials that you can follow.
You can even get started on smart contracts that would run on your nodes to enable you to make a wide range of Dapps. For that, check out Solidity.