Ah, my favorite, working with lists in FrontPage, what a breeze!
In your FrontPage Formatting Menu there are four buttons grouped together; Numbering, Bullets, Increase Indent, Decrease Indent. This is the power behind creating properly nested semantic lists. But, you have to understand how lists work first before beginning down this trek. I'll assume you've (not you inparticular) have read and fully understand the concept of lists. If not, you can read more here...
W3C - 10 Lists [w3.org]
Hopefully you are using FrontPage 2003 at this point and have access to the Split View option. If not, you'll have to switch between Normal and HTML view in previous versions.
For testing, just create a new page with no styling. You first need to become familiar with how the lists features work in FrontPage.
Insert your cursor at the beginning of the document. Click the first button for Numbering. That will automatically create the Ordered List elements...
Just type Testing 1 into the first list item for this session.
Now add another list item and label it Testing 2, and another labeling it Testing 3.
So now you've got this...
Let's say that Testing 2 is a sub-category of Testing 1 and we want to nest that list under the Testing 1 element. Highlight the Testing 2 line and then press the Increase Indent button twice in your Formatting Toolbar. You should now end up with this...
If you have FrontPage 2003 and are viewing via the Split option, you can see exactly what takes place each time you press that Increase Indent button. If you watched the above sequence, when you first pressed the Increase Indent button an opening <p> tag appeared. As soon as you pressed that Increase Indent button a second time, it was replaced with an opening <ol> tag.
The above should be enough to get you started on nesting lists. Try the test first, if you don't get the hang of it after a few trys, let me know and I'll expand the nesting from above. Just remember, to nest lists within lists, you need to use that Increase Indent button TWICE to generate the correct code. If you find the program inserting the blockquote element, then something isn't right somewhere. ;)
To remove the nesting, you use the Decrease Indent button and go through the exact opposite process. Remember, each time you nest within a nest, the buttons need to be clicked twice to go through the proper de-nesting sequence.