Yes, this is a common and often savvy move, sometimes known as a backdoor Roth IRA. There are many explanations.
You need to contact the IRA custodian (mutual fund company, bank, or brokerage) and request a conversion. You will owe prorated taxes on any traditional IRA contributions that were deductible, and on any gains to date.
The conversion is particularly beneficial if you don't qualify for direct Roth or deductible traditional contributions, since anyone with income can make nondeductible traditional contributions, and there is no income limit on conversions.