Add the necessary HTML to a Text Presentation element in the Form Builder.
When viewing the form in the Form Builder tab, the HTML tags will appear as-entered, but when an end-user views the form [by accessing the corresponding link to start the form from a Form Display part], the HTML will be rendered normally.

Example: How to add a link to a form
  1. In the Form Builder tab, drag a "Text" presentation element from the Available elements box to the Selected elements box in the desired location
  2. Click the pencil icon to edit the Text presentation element in the Selected elements box
  3. In the field labeled "Text:", enter the HTML for the hyperlink
  4. Click Save to close the element editing window
  5. Click Save or Save and Close in the Form builder to save your changes to the form design.
Example HTML for links:
Add the following to a Text presentation element to create a link to http://www.google.com :  <a href="http://www.google.com">Click here</a>

NOTES:
This technique can also be utilized to add HTML formatting tags, such as <b> or <i> to specific words or phrases within a Text presentation element.
Please consult external resources or a professional designer for more information about specific HTML tags and syntax, which is beyond Blackbaud's scope of support.