Questions about using a (STP) packer.

Hello. I'm a trans guy, shocker. But I'm thinking and have thought a long time about using a packer. Mainly an STP packer.

I don't know where to start. I've never packed in my life, because I'm scared that it'll just give me more gender dysphoria, but I'm studying applied biology for what I have to go outside a lot, and most of the time these places are without toilet. I always worry about where I'm going without toilet, and it causes stress. So I already have an STP device, but it's not dick shaped. just for emergency's. Because I'm trans and got dysphoria sometimes I do want to try packing, and seeing my study I thought an STP packer would be usefull, but I have no Idea where to start.

What kind of underwear do I have to wear? how do I keep it in place? Will it look like I'm hard constantly or is a STP even made to wear all day? Can I wear it all day? How do I take care of it? I have all types of questions and don't know where to start. I also don't have the bigfest budget, so I want to buy a cheap one, but do those just look natural in a pants? Idk. I would love some advice from ya'll where I can start and how a STP packer works. Thank you!