Allow only some check boxes to be checked. Loaded on page_load - asp.net

Question

I am dynamically adding asp check boxes to my page based off of number of rows in my db table, by ID. Also the checkbox is being assigned an ID from the db table. I also two columns in my db table "numberOffered" and "numberAllowed". My idea is on page load only allow the user to check say 3 of the 10 check boxes shown. I have removed a lot of the code I thought would be unnecessary. Thank you very much in advance.
For Each Arow As Object In ATable.Rows
For Each Brow As Object In BTable.Rows
If Brow(1) = a_ID Then
If Brow(2) = b_ID Then
Dim cbShown As Integer = Arow(5)
Dim cbAllowed As Integer = Arow(6)
Dim checkBox As New CheckBox()
End If
End If
Next
Next
checkBox.ID = Crow(0)
divcontrol.Controls.Add(checkBox)
EDIT:
Full Page_load sub
Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
If Not (Session("studentLoggedIn") Or Session("adminLoggedIn")) Then
Routines.LogOut()
End If
If Session("adminLoggedIn") = True Then
castVote.Enabled = False
castVote.CssClass = "btnDisabled"
Dim p As New HtmlGenericControl()
p.TagName = "p"
p.InnerText = "Vote button disabled. Only students may vote."
adminMsg.Controls.Add(p)
End If
Dim ballot_ID As Integer = CType(Session.Item("ballot_ID"), Integer)
Dim ballotName As String = CType(Session.Item("ballotName"), String)
Dim ballotsAdapter As New eVoteTableAdapters.ballotsTableAdapter()
Dim ballotsTable As New eVote.ballotsDataTable
ballotsTable = ballotsAdapter.GetDataBy3getBallotsByID(ballot_ID)
Dim sectionsAdapter As New eVoteTableAdapters.sectionsTableAdapter()
Dim sectionsTable As New eVote.sectionsDataTable
sectionsTable = sectionsAdapter.GetDataBygetsectionsByBallotID(ballot_ID)
Dim candidatesAdapter As New eVoteTableAdapters.candidatesTableAdapter()
Dim candidatesTable As New eVote.candidatesDataTable
candidatesTable = candidatesAdapter.GetDataBygetCandidatesByballotID(ballot_ID)
openBallotName.InnerText = ballotName
Dim section_ID
For Each row As Object In sectionsTable.Rows
If row(1) = ballot_ID Then
section_ID = row(0)
Dim sectionName As New HtmlGenericControl()
Dim sectionDescription As New HtmlGenericControl()
Dim divcontrol As New HtmlGenericControl()
Dim br As New HtmlGenericControl()
divcontrol.Attributes("ID") = section_ID
divcontrol.Attributes("runat") = "server"
divcontrol.Attributes("style") = "border: solid;"
divcontrol.TagName = "div"
br.TagName = "br"
sectionName.TagName = "h4"
sectionDescription.TagName = "p"
mainBallotDiv.Controls.Add(divcontrol)
mainBallotDiv.Controls.Add(br)
sectionName.InnerText = row(2)
sectionDescription.InnerText = row(3)
divcontrol.Controls.Add(sectionName)
divcontrol.Controls.Add(sectionDescription)
For Each Crow As Object In candidatesTable.Rows
If Crow(1) = ballot_ID Then
If Crow(2) = section_ID Then
Dim checkBox As New CheckBox()
Dim canImg As New Image()
Dim canName As New HtmlGenericControl()
Dim canBio As New HtmlGenericControl()
Dim rmImg As New Image()
Dim rmName As New HtmlGenericControl()
Dim rmBio As New HtmlGenericControl()
Dim canBytes As Byte() = Crow(6)
Dim canBase64String As String = Convert.ToBase64String(canBytes, 0, canBytes.Length)
Dim rmBytes As Byte() = Crow(11)
Dim rmBase64String As String = Convert.ToBase64String(rmBytes, 0, rmBytes.Length)
checkBox.ID = Crow(0)
canName.TagName = "h3"
canBio.TagName = "p"
rmName.TagName = "h3"
rmBio.TagName = "p"
canName.InnerText = Crow(4) & " " & Crow(5)
canBio.InnerText = Crow(7)
canImg.ImageUrl = Convert.ToString("data:image/png;base64,") & canBase64String
canImg.Height = 120
rmName.InnerText = Crow(9) & " " & Crow(10)
rmBio.InnerText = Crow(12)
rmImg.ImageUrl = Convert.ToString("data:image/png;base64,") & rmBase64String
rmImg.Height = 120
divcontrol.Controls.Add(checkBox)
divcontrol.Controls.Add(canImg)
divcontrol.Controls.Add(canName)
divcontrol.Controls.Add(canBio)
If row(4) = True Then
divcontrol.Controls.Add(rmImg)
divcontrol.Controls.Add(rmName)
divcontrol.Controls.Add(rmBio)
End If
End If
End If
Next
End If
Next
End Sub

Answer 1

You will want a variable (integer) for the amount of checkboxes allowed, then another variable for the amount of checkboxes currently checked, finally a List containing the name of each checkbox, (have all these variables as class fields)
then in your event handler something like
Sub Check_Clicked(sender As Object, e As EventArgs)
checked += 1
If checked >= NumberAllowedChecked Then
For Each a As CheckBox In MyCheckBoxList
If Not CheckBox.Checked Then CheckBox.Enabled = False
Next
End If
End Sub
I am not overly familiar with VB but I think this should set you on the right track on how to implement it for yourself
Edit: you will want to add in logic for if a user unchecks a check box that it will subtract one from 'checked;