How to create a form within anotheer form to accept differennt set of values

See more:

HTML

forms

I want to create a form within another form
FOR EXAMPLE
if there is are 2 input radio buttons
cash and kindness
then if a user selects cash option then another data field should open asking how much he wants to donate in cash and if he selects kind then a list of checkboxes must open to select from
i donno how to do such a thing in forms since i am a new person to web

What I have tried:

<pre><div class="col-md-3">
      <div class="loc-widget form-widget">
                <h4>Want to help someone ??</h4>
        <h5 style="color:#fff;">Do you want to donate in cash or kind ??</h5>
                <ul>
                <li class="radio">
        <label  style="color:#fff;"><input type="radio" name="optradio">Cash</label>
                </li>
                <li class="radio">
        <label  style="color:#fff;"><input type="radio" name="optradio">Kind</label>
                </li>                               
                   <li>
                    <button type="submit">Submit</button>
                  </li>
                              
                </ul>
              </div>
            </div>

This is the form i have n i would like to know how to do what i desire