Asp.net - Building A WebService In ASP 4 - VB

I have a search engine that will use a webservice to search through my database to find 3 specific things. I don't even know if it will work like this, but I have a dropdown list on my main page to select Product, Feature, Description. From what the user selects, the webservice should then go to an if statement to use the correct SELECT statement and find results for the search.

Will someone help me figure out how to fix what I've written to make it work? Please don't be too critical, I don't have a lot of experience. I have also been researching SQL Injection because I have a lot of code that is vulnerable so keep that in mind when you look at my code.

I can't get the blue squiggly lines to go away that are underneath the DropdownList1.Value instances on the WebService page.

WebService:

<WebMethod()> _
Public Function GetCompletionList(ByVal prefixText As String, ByVal count As Integer) As String()
Dim Feature As String = DropDownList1.Value
Dim Description As String = DropDownList1.Value
Dim Product As String = DropDownList1.Value

[CODE]..........................

Default.aspx page - Here I need the dropdownlist to tie to the database somehow.

<asp:ScriptManager ID="ScriptManager1" runat="server">
<Services>

[CODE]........................