Assuming you told Blue Prism that your Application Model is a browser-based program (this would show up in the creation wizard), it should be another option in that dropdown. Specifically, it will say Navigate.
As an absolute last-resort (note: this is not recommended), you can Win32 surface automate the URL input field, then use keystrokes to insert the text and hit Enter. AA automation to click the 'Go' arrow in IE may break on secured websites, as the element doubles in width.