There's a lot of things that require easing into them, things you aren't normally able to do right off the bat. The thing idea can be applied to anal. You need to start with something small and work your way up to something you really enjoy. I need you to go clean your asshole, make sure you're really clean. You can use gloves if you want, but you will likely need a lot of lube. You're going to want silicone lube for this. You will need to get into a good position to allow your fingers to enter your asshole with ease. If you follow my instructions well, you can learn to fuck your ass with one finger until you're up to your whole!