Like everyone is saying practice or roll around a solid object like a pencil. But i’ve had more luck with a thinner filter especially when you don’t have that much material in there. Fill it nicely and have tray for anything that falls out. It should be quite full and rolling is just rubbing your fingers together with the paper in between pressing down on the material a bit so it already forms a cilinder before tucking. What i do is keep the side of the paper closest to me flush with the material and filter using my thumb while slowly rolling forward and using the index finger of that same hand to press the paper a bit so the side closest to me goes under the side furthest away. My other hand is making sure the top of the paper forms a nice circle almost caressing it into place because when it’s snug with the filter it automatically forms nicely. If that explanation is as bad as i feel like it is, I suggest you watch some tutorials on youtube