heres how to do that, I added bootstrap to the page, to make the elements nice looking, basically you need to add a variable="#myVariable" attribute to the textbox to set the variable and for the button a onClick="ubot.runScript('myScriptHere')" to the button which fires the ubot script edit you meant the UI designer not panel, well this is still pretty much how that works
ui html panel("<head>
<link rel=\"stylesheet\" href=\"https://cdnjs.cloudflare.com/ajax/libs/bootswatch/3.3.7/cyborg/bootstrap.min.css\" crossorigin=\"anonymous\">
<style>
div\{
text-align:center
\}