Tucking can be hard if you’ve not done it before, so here are some resources for beginners. Note that it should not be painful, only uncomfortable at first. If you feel any pain, you are likely doing something wrong unless you have unique anatomy.
Guide (with pictures)! https://www.ohsu.edu/sites/default/files/2022-03/Gender-Clinic-Safe-Tucking-Handout.pdf
Guide (informative, with links) https://www.prideinpractice.org/articles/transgender-genital-tucking-guide/
Pride in practice is an all around great website. It has resources for persons in need to obtain gender affirming resources (gaffs, binders, etc) for free. The person in charge of the site also has a company for sale of these items which you can find on their website if you are interested (I don’t want this to be seen as an advertisement, so I’ll leave that to you).
Please share any resources or items you’ve found helpful for tucking if you have them!
P.S.: Please hide any NSFW images/content behind a spoiler: this post will not be marked NSFW.