Upload Templates
The SelectFilesButtonTemplate allows you to modify the Select Files... button. It lets you change the default text of the button and include custom content like an icon or image.
Using Upload SelectFilesButtonTemplate
<div>
<TelerikUpload>
<SelectFilesButtonTemplate>
<TelerikFontIcon Icon="@FontIcon.Upload" />
Click to Select Files for Upload
</SelectFilesButtonTemplate>
</TelerikUpload>
</div>