Firstly, define a variable `usernum` and let's use 10 as an example. Then, define another variable `summedvalue` and set it as 0 initially. This variable will hold the sum of all odd numbers up to `usernum`.
Next, we start a for loop. This loop will go through each number in the range from 1 to `usernum` inclusive. That's why in the range function we provide `usernum + 1` as the second parameter.
Now, for every number `i` in this range, we check whether it is odd. A number is odd if it gives a remainder of 1 when divided by 2. In other words, we're checking if `i % 2` is not equal to 0 (`i % 2 != 0`).
If the current number `i` is indeed odd, we add it to `summedvalue` (`summedvalue += i`). Then, the loop goes to the next number and the process repeats itself until we've considered all numbers from 1 to `usernum`.
Finally, when the loop ends, the value of `summedvalue` is the sum of all odd numbers from 1 up to (and including) `usernum`. Return this `summedvalue`.
In the case of `usernum = 10`, the odd numbers between 1 to `usernum` are 1, 3, 5, 7, and 9. When you add them together, you get 25. That's why in this case, the result will be 25.