I have built about 7-8 Versa Wings, and every one of them has been in a pusher configuration. They are a little tricky to launch them if you've never launched them before. If it's never been trimmed out, my first suggestion is to grab someone else who can throw it into the air for you so you can keep both hands on the controls for the first time.
Before launch, make sure that your Versa Wing is balanced on the balance points. When I make my planes, I will take a skewer or my linkage rod and push it through the foam to mark that balance point from the plans. If you're using a small diameter linkage rod, take your cutting blade and put the tip of it in the hole and twist it around a little. The purpose of this is to make it so you can easily feel that hole from underneath the wing. You don't need a giant, gaping hole in the wing, just something big enough so that you've got a nub there. Something maybe 1/16"-1/8" in diameter.
With those holes, you should have your battery that you're going to fly with in the plane. If the wing doesn't balance out (i.e., it's too tail heavy in a pusher configuration) YOU NEED TO ADD NOSE WEIGHT. I will usually take my glue gun and squirt a healthy amount of hot glue into the very tip of the nose, with the battery out. This adds weight, and it seems to help make my nose a little more durable from the inevitable nose dive/crash/skid on the runway when we're doing our "horseshoes" game during our Trifecta sessions.
Other guys in my club have glued in some pennies, and still others have put the lead weights and tungsten nose weights in to keep the plane balanced. Whatever you do, MAKE SURE THAT WING IS BALANCED BEFORE YOU LAUNCH IT!!! Pusher configuration wings are finicky with being tail heavy, and if it IS tail heavy, forget trying to control that sucker easily - it'll act like a whale breaching throughout your entire flight.
I saw some people suggesting that you use your sub-trim to get the elevons to sit up a bit. While that works, and it's certainly not wrong to do it, I personally find it takes out some of the throw that I may need for quicker response, especially when I'm flying in combat. To remedy that, I will instead run a linkage stopper through the hole of the control horn. Then, I can put it flat on a table, and adjust it so each side is sitting up evenly, using the linkage stopper to lock it in place instead of adjusting out through the sub-trim. One warning, because I have done this myself several times - If you are using the linkage stoppers, MAKE SURE YOU TIGHTEN THEM DOWN SO THEY DON'T SLIP!!! I have launched with one being loose, only to have the wing spiral into the ground, or get up in the air for a launch and then have it slip to thud into the ground in a heap because I didn't tighten it down. Easiest way to test that is to get it tight, then plug in your battery and check the elevons that they're moving up and down in the correct directions. If they are, you'll not only have made sure it's good, but you'll have gotten some of your pre-flight check out of the way!
Another thing I do with mine is I set up rates on a 3 way switch and run 50% Dual Rates/30% Expo on AIL/ELE on position 1, 65% Dual Rates/30% Expo on AIL/ELE on position 2, and 80% Dual Rates/30% Expo on AIL/ELE on position 3. Now, that's for what *I* fly at for my combat Versa Wings; you may find you want something more like 50-60-70% for low, med. and hi rates. The reason I do this is so that, on takeoff, I can put it to a higher rate for the initial launch, and give some up elevator when I launch it.
I'll usually set it for my Mid rate for launch, put throttle to 100%, and give it kind of a "backhand tennis" throw with my left hand - if you can imagine swinging a tennis racket to hit a tennis ball, it's a lot like that. You don't want to snap your wrist, just keep it in a short toss, maybe moving your arm about 45 degrees out from your body, and going up and out. You're not launching it at a hard angle up into the air, just trying to get the nose of the wing to go up at maybe a 30-45 degree angle from the ground when you throw it.
I do it this way so that I can have my right hand on the right stick, working the aileron and elevator, and so I know where that prop is at all times, so it can't cut me. I do the 100% throttle until it's up in the air at least 40-50 ft up, and then start leveling it off to trim it out and adjust it. You may find that launching at mid- rates is giving you too much play on the launch, and may want to go down to low, which is perfectly fine - do what works best for you.
Now, If I find that my plane is nosing down from that throw, and I'm pulling up on the stick and it's not climbing immediately and gliding down, I'll cut the throttle and try to just let it pancake onto the ground without too much damage. Odds are, I need to put in a little more up elevator (which, if you used the linkage stoppers, you can adjust it easily rather than having to run your trim to the full end of the spectrum!) for it, so that it'll fly nicely and I can get it trimmed out appropriately for normal flight.
This is my process for my Versa Wings, and it's been fairly successful! I've only had a few that have gone wonky on flying, and it's usually because i have something loose, or a wing that's pretty well damaged. It's the process that's worked for me specifically, and hopefully there's some good tips there that will help you be successful in getting your wing launched.