How can I paint kitchen tiles

what are they made of?

Here's a how-to: https://www.todayshomeowner.com/how-to-paint-over-ceramic-tile-in-a-bathroom/ The most important points are that you have to prep the existing tile, and you have to use a bonding primer if you're applying latex paint.

Rustoleum has a kit you can buy i did my shower tiles it looks like stone when funished but they have one for counter tops and kitchens it is a 2 step process if you dont want to spend $100 for the kit then go on youtube. there are videos showing what materials to use there is also a product called gripper. that allows you to paint your tiles with regular paint.

Good points above. If you are only painting 1 colour, I have used Krylon Fusion paint in the past withour primer, and it held up really well on my kitchen backsplash. Do not use it if you have a gas flame nearby.