Here at FacebookEmoticons we have simplified how to share our custom sticker in chat. Please look below at a visual step-by-step process on how this is done.
1. First you need to find the sticker you want to send. Then hit the Send In Chat button.

2. Next you still see the following screen:

3. Click on the Name field and type in the name of the person you want to send the custom sticker to. If you want to add add in a personal message you can as do that as well. When you have finished hit the Share Photo button and the customized sticker will send to your friend
Enjoy! Check out out our complete collection of custom stickers in our sticker section here.