Vlad is pissed because one of his clients hasn't paid him in months. He wants you to teach him a lesson.
Once you're outside, you'll learn about hailing a cab. Use the button displayed, and Niko will whistle for a cab. If there's one near by, you'll be able to get into the vehicle as a passenger by holding down the enter vehicle button for about a second. Once inside you'll be asked where you'd like to go. Pick the yellow destination and you'll be taken straight to the shop that you need to visit. Otherwise, grab a car and drive there yourself.
You Asked For It...
Once you arrive, the guy won't let you in, so you'll be told to throw something through the shop window. Head behind the building opposite the shop and you'll find some bricks. Pick up one of those, walk across the road and throw it through the window.
This will scare the guy inside and he'll offer to pay Vlad. Now you've gotta get the money back to Vlad, so either grab a car, or take a taxi back to him and watch the short cutscene.
- Taxi's are a great way to get to your destination more quickly. They cost a little bit of cash, but can save you 5 minutes of time on certain missions by allowing you to skip long journeys.