From endpoint to plane (extracting)

Hi, i am new to scripting in GH and need your help with this:

I want to make a circle at 90 degrees angle from a line created in VB.

I thought i could extract a plane from the line using a similar method to this one:

 Dim EndPointA As Point3d = startLine.To + VectorA

Then use the plane for my circle.

This is my code:

    Dim LineA As line
    LineA = New Line(pt1, pt2)

    'Here i wish to make a plane from the endpoint
    'Of the New line (LineA) And use the New plane For the circle below

    circlelist.Add(New Rhino.Geometry.Circle(lnIn, 2))

    linelist.Add(LineA)

Also if you know any good sites for finding vb, sdk, gh code please share some, i know programming but fail to find the specific grammar.

Thanks!

f