Bootstrap DropDown question (newbie)

Hi, can someone help me with a bootstrap question? I am not a developer, altough I try to learn it a little.

I am trying to understand how a "connect4" game works and I want to make a drop down list that is in a working game to bootstrap since it has a better layout.

I tried but I can't figure out

• How the player part works in the original code, I guess it is related to the javascript but I don't know how to use it in bootstrap.
• How the value part works in the original code
• How to make it so that if you select something it keeps being visible as this is your choice in the bootstrap version.

I copy paste the code here of the HTML dropdown.

Can someone help me to bootstrap this please

    <form id="players">
        <label>
            Yellow =:
            <select name="player_1">
                <option value="0">Een echt persoon</option>
                <option value="1">De computer speelt makkelijk</option>
                <option value="2">De computer doet een beetje gemeen</option>
                <option value="3">De computer doet gemeen</option>
                <option value="4">De computer doet belachelijk gemeen</option>
                <option value="5">De computer doet idioot gemeen, kan jij winnen?</option>
            </select>
        </label>
        <label>
            Red =:
            <select name="player_2">
                <option value="0">Een echt persoon</option>
                <option value="1">De computer speelt makkelijk</option>
                <option value="2">De computer doet een beetje gemeen</option>
                <option value="3">De computer doet gemeen</option>
                <option value="4">De computer doet belachelijk gemeen</option>
                <option value="5">De computer doet idioot gemeen, kan jij winnen?</option>
            </select>
        </label>
    </form>

    <div id="board"></div>

  </div>
</div>