Ok, you are now in business, congratulations!
The experience will teach you a lot about how business works. Taxes are a big part of that. You not only have sales tax to deal with, you also have income tax, too. You'll need to start keeping a good set of business records to support what you report and pay to the tax agencies. This means you should at a miminum have a record of sales (you can keep it on computer spreadsheet) in which you list the goods sold (especially important if you keep an inventory of goods), the amount of the sale, the date of the sale, and the amount of the sales tax you charged and collected on the sale. You also want to record each of your business expenses, too, and keep copies of receipts or other documentation to back that up. Whether you need more than a simple ledger for income and another for expenses depends on the details of your business, like what you are selling, how much you are making in the business, etc. But get in the habit of keeping good business records. It is essential to have them not only for tax purposes, but also if you need to get a loan for the business and also simply for you to evaluate how your business is doing.