By simply selecting the "+" mark with Create a bot in the My Bot page, you will be redirected to a page like the one shown below.
Selecting the content
After you are redirected to this page, you have to select the creation method that suits your needs. Then, you can continue the bot-creating process.
If you select the "Create bot using my content", you will be redirected to a view as shown below, where you can enter the details that are needed for the bot creation process and continue.
PC view
Tablet view
Mobile view
Finally, you can enable the plugin in YouTube, as well if needed, by selecting the "Enable this plugin in YouTube" option available.