When you count to 10, the numbers are

1, 2, 3, 4, 5, 6, 7, 8, 9 and 10.

The numbers from 10 to 100 are:

10, 11, 12, 13, 14, 15, 16, 17, 18, 19,
20, 21, 22, 23, 24, 25, 26, 27, 28, 29,
30, 31, 32, 33, 34, 35, 36, 37, 38, 39,
40, 41, 42, 43, 44, 45, 46, 47, 48, 49,
50, 51, 52, 53, 54, 55, 56, 57, 58, 59,
60, 61, 62, 63, 64, 65, 66, 67, 68, 69,
70, 71, 72, 73, 74, 75, 76, 77, 78, 79,
80, 81, 82, 83, 84, 85, 86, 87, 88, 89,
90, 91, 92, 93, 94, 95, 96, 97, 98, 99,
100.

A hundred is 10 sets of 10. A thousand is 10 sets of 100 or 100 sets of 10.

You can see a pattern in these numbers. Each time you count up, the right-most digit increases by 1 unless it is a 9 (24, 25, 26, 27, 28, 29). If the right-most digit is a nine (such as 29), then digit to the left increases by 1 and the right-most digit becomes 0. The next number after 29 is 30.

The first digit on the right is called the one's place. It tells how many ones there are in the number that are not included in the full sets of ten. In the number 24 there are two sets of ten plus 4 ones.

The next digit to the left is called the ten's place. It tells you how many sets of ten are in the number. The number 24 has 2 sets of 10.

If there are more than 2 digits in the number, the next digit on the left of the ten's place is the hundred's place. It tells you how many sets of one hundred are in the number. 724 has seven sets of one hundred, 2 sets of 10 and 4 ones.

A number with 3 digits is between 100 and 999. The name of the number is the name of the first digit followed by the word "hundred", and then the name of the final two digits. For example, the number 507 is named "five hundred seven", the name of 784 is "seven hundred eighty-four". If the last two digits are 0 then the name is just the name of the first digit followed by hundred (e.g. 600 is named "six hundred").

To count up, the hundreds portion of the number stays the same until the last two digits are 99 and then the hundreds place name is increased by one and the two last digits will become 00. For example,
299 = two hundred ninety-nine
300 = three hundred
301 = three hundred one

The number 24 could be represented by:

1	2	3	4	5	6	7	8	9	10
11	12	13	14	15	16	17	18	19	20
21	22	23	24

The 2 in 24 comes from the two full rows of 10.
The 4 in 24 comes from the last row which has 4 in it.