Look up hair extension tutorials on Youtube. I personally would curl them!
What can I do with my hair once the extensions are on?
Depending on the type of extensions you have in, you should be able to use any of your favorite heat styling tools, but be careful of temperature. Some synthetic extensions recommend not exceeding 320 degrees or so. You can also wash and brush your extensions while they're in, but it's generally not recommended to brush while the hair is wet.