The designers should have added various pre defined styles to your site (i.e. H1, H2, H3) , to make use of these you need to edit the required page by going to Tools and then selecting CMS - Page Editor.

Step 1

Go to "Tools" and then select "CMS - Page Editor"

Step 2

Then Select a page to edit, by clicking on the required "edit" icon under status

Step 3

You then need to highlight the text that you wish to make a H1

Step 4

Then from the Format menu select "Heading 1"

Step 5

The heading should now be added

Step 6

To remove a H1 tag, re-highlight the the text that has a "Heading 1" on it, then select "Normal" from the Format dropdown at the top of the page.

Step 7

Then save the page