u/AnywhereParticular28

You want to guide it with one hand inside, and push from the "root"/bottom to the tip, to move the blood to the tip, kinda like massage, also can switch hands it helps to push it in. And relax of course. you can stuck it in with your finger. Experiment. Some day its easier and some harder, Dont force it. Have fun and enjoy.
Another option is to sit on your hand with a similar hands movement:
PRO TIPS: Stretch firsts ;) and use good lube. Unfortunately shouldn't be too hard - it makes it harder hehe

Wanted to do something special for the video, but my ass was super tight today, It took me like 1 hour to fit "everything", but. here it is. Also got like 20 other videos because of that. Let me know if you want to see some more.