Sorry, but I guess this is related to your other post. Unfortunately, flash textfields are very limited and they don't support tags like <h1> or style tags or anything. Wordpress is a blogging platform, where you are actually editing the page that the browser renders, and this is very powerful. Flash textfields (Imagevue text pages), are not rendered by the browser, but instead are just a simple TEXT FIELD which is rendered by flash. This textfield only supports a few purely formatting options, as outlined here:
https://www.photo.gallery/documentation/textpages/
Normally, I would recommend just keeping text pages basic because they are not beefed up for much more. A workaround for creating a pseudo heading class for example, would be to create your own style in your theme CSS:
.header1 { font-size: 20px; font-weight: bold; color: #EFEFEF }
Then you could apply this in your text, by clicking to edit the html directly:
<span class="header1">My Header Text</span><br/>The normal text ...