Not sure about online guides, but it's simplicity itself to do.
Put a tablespoonful of seeds at the bottom of the jamjar and cover them with lukewarm water. Set it aside for an hour or so.
Meanwhile find something you can use to stretch or fix over the top of the jar to act as a sieve.
A bit of tshirt will do if that's what you have, one of the sink cloths does too, I used a bit of net curtain at first. I fixed it on using an elastic band.
Don't pour icy cold water onto your seeds, don't go too hot either, just take the chill off the water.
I rinse and gently swish mine with fresh water every time I pass the sink, but so long as they don't sit sodden wet and drown and don't dry out, they'll sprout
Some folks manage with just a couple of rinses a day. I admit mine get more, but I'm at home, so it's easy. Rinse with clean water and set the jar so that it drains towards the opening. You can just lay it on it's side on the draining bit beside the sink and it'll do fine.
Best of luck with it
I like the sprouts, they're a good addition to the diet, excellent in a piece and really nice with saladings, or good to munch just like a wee bowl of nuts.
M