webbroiwser control with drop down menu needs to be selected

[cobusd@intekom.co.za]

I use VB.Net 2017, Windows form with webbrowser control. I can insert username and password. On the next page that I navigate to I must select a category and sub category. I've been struggling for a week and tried any thing that remotely resembles the problem
Supplied is the source code form website problem areas are marked in re an green. Please get me in the right direction

Please see attachment

I Need to fill in the options in red and green
1. Main category
<div class="input-group col-lg-12 col-md-12 col-sm-12 col-xs-12" style="padding-bottom:15px">
<label for="category" class="control-label col-lg-4 col-md-4 col-sm-12 col-xs-12">Main Category</label>
<div class="col-lg-8 col-md-8 col-sm-12 col-xs-12 ">
<select class="form-control" id="category" name="category"><option selected="selected" value="">Select your Category</option><option value="17">Beauty &amp; Spas</option><option value="9">Building &amp; Construction</option><option value="4">Business &amp; Finance</option><option value="15">Community</option><option value="12">Education</option><option value="3">Employment</option><option value="7">Event Planning</option><option value="20">Farming</option><option value="19">Healthcare</option><option value="18">Holidays &amp; Travel</option><option value="10">Home &amp; Garden</option><option value="21">Industry</option><option value="16">Leisure</option><option value="11">Pets</option><option value="2">Property</option><option value="14">Public Services</option><option value="8">Restaurants &amp; Nightlife</option><option value="6">Shopping</option><option value="13">Sports &amp; Outdoors</option><option value="5">Technology</option><option value="1">Vehicles</option></select>
</div>
</div>

2. Sub catogery
<div class="input-group col-lg-12 col-md-12 col-sm-12 col-xs-12" style="padding-bottom:15px">
<label for="sub_category" class="control-label col-lg-4 col-md-4 col-sm-12 col-xs-12">Sub-Category</label>
<div class="col-lg-8 col-md-8 col-sm-12 col-xs-12 ">
<select class="form-control" display="none" id="sub_category" name="sub_category"><option value="0">Select your Sub-Category</option></select