Fun Factory Share - Tips, Tricks, and Advice?

I just received my first strapless strap-on, the Fun Factory Share from Eden recently and I was incredibly excited to try it. I'm going to be using the Share on my partner anally, but as we are in an LDR it'll be a few months before I get to try it out in person. While this is disappointing, it also means I have a few months to get used to it! Because Fun Factory's "manual" is pretty much useless (come on, I paid $105 for this thing and you can't even be bothered to write instructions for this specific toy? ) I took my best guess as to how to use it the first time. Since I don't happen to have any lube on me, I opted to play with myself a little first and came so that I'd be nice and lubricated, as the bulb, while not huge, is a pretty moderate size. I stood to insert the share, which in and of itself was a bit awkward--I found that it kept slipping out while trying to get it in. Once in, it stayed, but not well. I could move it slightly, but I was in constant fear of having it fall out... Although the shaft of the toy was not lubricated, it barely took ANY effort to pull the thing out when pulling on in the same manner sex would. I'm not sure if I didn't have it situated quite properly or if maybe it just doesn't fit my anatomy, but the future for this toy is looking a little bleak right now.

I'm not ready to give up yet, though! I have decently strong PC muscles, but I intend to start doing kegels to get them even strong in the next few months. Even still though, can anyone give me any tips for using this toy without a harness? How much lubrication do you use when putting it in? What positions (standing, squatting, laying, etc) is best for insertion? Should you let it sit for a while before attempting to use it?

I really wish the instruction manual were more helpful--I'm honestly rather disappointed by both the packaging and instruction manual, but that's another complaint entirely!

Thanks for the help everyone!