Web Forms
Default Values
You can define default values for fields in the URL of your form. To do this, find the unique ID of the field by opening your template in the template editor, selecting the field, and opening the "Name, view & display" left menu. The unique ID is the first entry.
Once you find that ID, you just need to add it to your web forms URL as a parameter with a prefix of: df_ and then an equals sign and the value you want to be the default. It would look something l like this:
df_4e55d1d6027ddd36=Text+to+display.
Make sure that you URL Encode your string value. You can add these default parameters to the URL used in the Iframe where you embed the form to your own website, or if you are sending the link directly to someone, you can put them into the link.
Example
Here is a link to a form with default values in the URL. If you click this link an example form will display with the text "This is default text" in the first field. If you look in your web browsers address bar you will see the following URL. Change the value after the &df_4e55d1d6027ddd36= and press enter in your address bar to see the default value change.