What size cheese are you making?
Mkay. I tend to wax verbose on this topic, so I'll just sketch out a simple plan for you and explain the basics.
Whip up, in a little tupperware, a ~8-16% brine, with about 1/6 of the water being wine. The salt and alcohol combine to kill off organisms on the surface while allowing the linens to grow. Do not make a new one. By the time you'll have used it enough for it to be not good, at least if you're making cheese regularly, you'll be able to tell. Don't replace it until it's really really bad and stinky and horrible. Because that's what you want. If you don't have linens yet, don't worry. Wash the cheese, you may not get much the first few cheeses, but pretty soon you'll have a lovely bright linens. See here
for progression on my cheeses. Once it's established, it'll take a few days before you see it.
I digress. So with a brush, whether a cleaning-type or a finger-nail type, preferably natural but it doesn't have to be, dip it a little way into the brine. Then smear this around on the outside. Let it stand outside until it's dried off until it's moist/tacky rather than wet (this also gives time for more linens to come), then put back in cave. Once you have linens, you'll be able to tell, because when you get the cheese wet you'll be rubbing around a sort of slimy substance. Do not wash this off. Just smear it around with your brush, don't be afraid to handle it with your hands. The tricky part here is getting the right moisture on the rind. If too wet, the linens will thrive too much and the cheese will taste like linens. If too dry, then other molds can take over. If really too wet, it gets blue mold and if really too dry it cracks.
Follow a schedule of 1/day per first two weeks or so, washing one side per day, then 2-3/week for another 2-3 weeks, and less often over time until it's established a nice firm rind.
It is not advised to dip your brush into the liquid more than once, or you risk getting it too wet.
This advice is all for smaller cheeses, I generally make 2 pound makes. With larger wheels, you want to make the linens thrive more and get a really thick and nice skin on the outside. But if you do this on a smaller scale, it ends up with linensy cheeses.
Also, read this.
Everything I know about washed rinds, I first got from him and then tried here. The Swiss have it figured out.
Please ask if you have any questions.