God can use you, however old you are - whether you are a brand new Christian or an old and whiskery one... He can use you in many different ways at home, at school or at church.
You will need to ask the Holy Spirit to help you see where you can be used.
James 2:17b (TLB)
Faith that doesn’t show itself by good works is no faith at all—it is dead and useless.
When I do this prayer with children I
talk through the different ways God can use them. Quite often it's just common sense - begin with doing what you should be doing. Tidying your room and doing your chores without complaining for a start!
Being used by God isn't just about being up front, leading hundreds to Jesus, or leading worship etc. It's also being faithful in other things - shopping for someone who can't get out, helping in the garden for some one who can't do it themselves. The list could go on and on.
Micah 6:8 tells us
The Lord has told you, human, what is good; he has told you what he wants from you: to do what is right to other people, love being kind to others, and live humbly, obeying your God. (NCV)