Sales tax if you sell to anyone in your state, if your state has a sales tax. You collect it from the buyer and remit it to the state. You get a sales tax ID from the state for that.
Federal, and state and local if they exist where you live, income tax.
Self employment tax if your net income for the year is $400 or more. That's for social security and medicare, and you calculate and pay it when you file your federal tax return for the year.
The se tax is around 14.1% of your net. Income tax % depends on how much you make and where you live. Sales tax rates are set by the state - but you aren't really paying that anyway, just collecting it and passing it on to the state.