I'm sorry I live too far away to help, where did you get them from? Maybe you could go back with one of them for a demonstration to give you confidence?
Also, I just wondered how you are picking up your hens? If held correctly they can be 'operated on' with no trouble or flapping or scratching, they will just settle down calmly so you can see what you are doing. Wing clipping is really only like toenail cutting, removing bits that have no feeling, and along with routine care like cutting their toenails now and then, and examining them for lice etc, is something that's much easier if you can hold them confidently.
Put your hand over the hens back, fingers pointing forwards down either side of her neck. Often she will crouch at this point, which helps. Slip your other hand under her tummy, fingers forward, and get hold of her legs, with one or two of your fingers between them to cushion them. Close your fingers so you have a firm hold on her legs. At the same time, lift her and get your other arm over her wings and support her weight. So long as you keep hold of her legs, she can't get way and she can't hurt you. Never try to lift a hen with your two hands over her wings, or she will panic and scratch you with her unrestrained feet as you pick her up. For wing clipping have somewhere to sit down with her, then it helps at this point if one person holds and soothes the hen whilst the other person extends one wing and has a calm look at the feathers. The videos you've been watching will have showed you which feathers to clip, and how much to take off. So long as the hen is calm and still, there's really no problem in actually giving her the 'haircut.'
However, it may not even be necessary to clip their wings, and it's not always very effective anyway. Many can fly out even with a wing clipped! What sort of hens are they? Many hens are too busy eating lovely grass to bother about flying out, although young birds and lighter breeds are more likely to get airborne. Once they've settled down and know their territory, ie your garden, they probably will stop trying, even the ones who did at first. In any case you won't need to do it more than once, as when they've settle down with you and get into lay they won't bother -unless they are Leghorns or Leghorn hybrids, who do go on flying out. I did clip my first hens, but haven't done so since because I found they had difficulty in shedding the feather stumps when the time came to moult them out and grow new ones.
P.S. Edit; I've just read your other post and remembered you have exbatts, so I would try just letting them out and observing them. At their age, and with their history, they are most unlikely to fly out of the netting circle, in fact it would be amazing if they did. Probably no problem!
