I found a set of d4-d20, but apart from the d6 and the d4 (with the help of How do I read a 4-sided die?), I'm not sure how to read them and I'm new to these kinds of dice.
How do you read a d8, d10, d12, d20, d24, and d30?
For any normal die (and most other dice besides) except the d4, you read it by taking the number on the uppermost face after it has been rolled, just as you do for the d6. Though of course these other dice have more faces than the d6, at the end of the day they will rest the same way; one face will be flat on the rolling surface, and the result shown on the face opposite that.
D4s exist in a couple of different versions. The two primary versions are both pyramid in shape, but they are numbered differently. Set the die flat and look at all the sides - either the tip of all three visibles sides will match (and be upright), or the number at the base of all three sides will match. There also exist "eight sided" and "twelve sided" dice that are numbered 1-4 multiple times (twice or thrice respectively). Even though they have more than four sides, they generate an even distribution between 1 and 4, so they are still d4s.
The d100 is another special case because you are not normally expected to roll a 100-sided die for that - though they do exist, because they're nearly spherical it can be more awkward to accurately identify which face is actually on top, and they tend to roll further than is ideal. Instead, the common way to roll a "d100" is to roll two easily distinguishable ten-sided dice (e.g.a red d10 and a blue d10) with one of them representing the 1s digit and the other representing the 10s, with the convention that a roll of 0 and 0 represents 100. The d100 is sometimes referred to as a d% (said "d-percentile").
The commonly used set of dice in RPGs is the range of d4, d6, d8, d10, d12, d20, and d100. The d2, d3, and d5 are sometimes also used, but not typically as "real" dice. A d2 can be represented by flipping a coin, or rolling any even-sided die and calling odd-numbered faces 1 and even-numbered faces 2. d3s and d5s are usually represented by rolling a d6 or d10 and halving the result (rounding up).