<p>If it said "oneword", then I could write "#oneword", but what do I write when there is a space in the word?</p>

You can't have multiple words for the id, but you can for class.
```
```
<p class="one two">lalala</p>

.one {
    color: black;
}

.two {
    font-weight: bold;
}
```
```