You can use half whole wheat and half bread flour or just use 1 kind of flour as long as the weight is 60 grams. As you feed and discard, you can even change up the flours a bit.
Weigh your jar and jot down the weight in ounces or grams. The jar I use weighs about 10.3 oz or 290 grams.
Put flour in the jar, then pour in the water and stir with a long spoon or butter knife. Wipe the rim of the jar clean. The jar plus the starter should weigh 290 (jar), flour (60) and water (60) so about 410 grams. Doesn't have to be precise, but knowing the weight of the jar helps make discarding easier down the line.
Cover the top with an inverted coffee filter and secure with a rubber band. Let stand overnight.
The next day, give it a stir and discard all but 60 grams. So if your jar and everything in it weighs 410 grams, just pour out 60 grams. After you've discarded 60 grams of starter, add 60 grams more of flour and 60 grams of purified water. Stir well and cover with the coffee filter.
Every day for the next 4 days, discard all but 60 grams, then feed with 60 grams of flour and 60 grams bottled water, stirring well each time.
When the sourdough is active and bubbly, use what you need for a recipe (usually between 60 and 120 grams), keeping 60 to 80 grams behind. Feed twice a week with 60 grams flour and 60 grams of water.