I mean bigger than the usual size.

There are numerous ways... But you could try something like:
<h1></h1>
or
<font size="7"></font>

And their are several other ways, but those ought to be the easiest.

<font size="1-7">Font Goes Here</font>

Change the stuff in bold. the higher the number, the bigger the font.

You can also use a Style Sheet.

If you're willing to use a little CSS, you can make it any size you want. Like so:
<font style="font-size:24pt">text here</font>
You can change 24 to any number you want (remember that it's in point-sizes though, the same as you would use in a word processor document). :)

If you're willing to use a little CSS, you can make it any size you want. Like so:
<font style="font-size:24pt">text here</font>
You can change 24 to any number you want (remember that it's in point-sizes though, the same as you would use in a word processor document). :)
that is a good thought, but i would suggest using SPAN instead of FONT if you are going to move into css.

also mention that they can use PX instead of PT for the size if that helps.

<Font> is alright, but I think there is a limit to the biggest size you can have - I think that you can go larger with <span>