Keyboard fingering refers to the rules about which finger should press which key. Building consistent fingering habits is the key to fast and confident touch typing.
The standard fingering rules are guidelines, not strict rules. Everyone has different hand sizes, and keyboard layouts can vary slightly. What matters most is that you always use the same finger for a given key - your brain remembers the movement, not the rule.
Two habits hold beginners back more than anything else: glancing at the keyboard and typing with just a few fingers. Stay with those and you'll plateau around 20-30 words per minute and get stuck. Touch typing starts with using all your fingers, even when it feels slower at first. Force yourself not to look at the keys - even at the cost of speed in the first few weeks.
The pinkies need separate attention - they're weaker and less nimble than the index fingers, yet they're supposed to handle plenty of important keys (a, q, Shift, Enter, p, ;). It's easy to fall into the trap of "swapping fingers" - for example, hitting A with the ring finger instead of the pinky. That habit comes back to haunt you and blocks further progress.
To produce a capital letter, hold Shift with the hand opposite to the one pressing the letter. To type "A", hold right Shift; for "L", hold left Shift. Alternating between hands like this is faster and less tiring on the wrists than using the same-side Shift.
After every keystroke, the finger returns to its home row position. When you reach for a key, don't drag the whole hand with it - only one finger moves. The rest of the hand stays on the home row, ready for the next letter.
Everyone makes typos - that's normal and unavoidable. Learn to correct them without looking at the keyboard: press Backspace and retype the letter while still looking at the screen. With time, your fingers learn on their own to hit the right keys, and corrections become automatic.
Once you consistently use the correct fingers for long enough, the habit forms on its own - and you'll stop thinking about it altogether. It will be slower at first, but the result will be lasting. 10 minutes a day gives better results than 2 hours once a week.