All around you are people in great need. Sometimes their needs are physical (such as those who don't have enough food, or are ill). But sometimes their needs are less obvious -- loneliness, discouragement, broken relationships, worries about the future, and so forth.
And yes, God wants to use you to help them. The Bible says, "Carry each other's burdens, and in this way you will fulfill the law of Christ (that is, the law of love)" (Galatians 6:2). It isn't always easy, and sometimes it may involve inconvenience and heartache on our part. But just as Christ left heaven's glory to suffer on the cross for our salvation, so He calls us to go out and serve others in His name.
Does this mean you have to change your whole personality before God can use you? No, of course not. God knows what you're like, and He can use you just as you are if you're willing. Peter was what we'd call an extrovert, while Paul's young friend Timothy was apparently shy and introverted. But God used both of them -- just as He can use you.
Don't worry about what you can't do, or the people you can't help. Instead, trust God to lead you to those you can help -- people who will feel comfortable with someone like you. Pray for others also, and consider volunteering in a food pantry or other ministry your church supports. You'll not only help others, but you'll find yourself becoming more confident.