First you have to make a wedge and a baton. The wedge can be made from wood, or a rock. Then you use the saw to saw a split that you will place the wedge in, and then pound the wedge with a baton.
I do this with a knife. baton the knife into it with the grain and then follow the knife with the wedge, as the wedge opens the wood, pull the knife out, and just continue to whack the wedge till the wood comes apart. Can use one wedge or start with a small one and work up. Good way to split clean grain stuff to get at dry wood inside.
You do need a full haft knife for it. I've also seen it done by someone who carried an old handleless meat cleaver for this purpose.
Which does get to what I do, if it's really awful out.
I find tinder, usually spanish moss or fine twigs underside of conifers. If there is birch - great, find a dead one. if there is cedar, get under the wet outside layer of bark and scrape with knife or rock, the resulting shaved bark is really good. cattails? awesome. dry grass, workable but hard to find when it's pouring out. Now, really, if I'm outside and know I will have to do this, I am preparing ahead of time and picking up these materiels as I walk. It's a rare thing that I all of a sudden decide "oh I need to make a fire" in the middle of a rainstorm and have *nothing*" So I usually have *some* bits of workable tinder
with me. Frankly, I almost always have a bic lighter. In the winter I may be doing this with dryer lint and a ferrocium sparker. Either way I need the rest of the stuff.
If I can find enough dry small stuff under conifers, or deadfall, break it off and get a good enough pile to get good and hot, and get it going. Once the fire's hot enough I can add wood that's wet on the outside and it will self sustain, but I need enough dry stuff first to get a decent little fire going with some coals and staying power.
If I can't find this by looking around. I will likely find some straight grain dry wood and split it as above. This make take some time, so anything I can find of small twigs or dead stuff that's dry from the underside of conifers will speed the process, but if I have to I'm splitting my way down to twigs for some of it. the key here is really to get to dry stuff.