Twitter is an ideal medium for an advertisement for your business and there are many ways that you can do this.
To start with open a Twitter account in the name of your business if the name is available. Don't worry if you already have a personal Twitter account, there is not a limit to how many Twitter accounts you are allowed to have.
If you want to know how to use twitter for business advertisement I would advise that you have a look around to see how other people...