So I kinda found a vba code that worked ok for my problem:

Sub ApplyOpenCommunicatie(Control As IRibbonControl)

Dim objPresentaion As Presentation
Dim objSlide As Slide
Dim objImageBox As Shape


Set objPresentaion = ActivePresentation
Set objSlide = objPresentaion.Slides.Item(2)

Set objImageBox = objSlide.Shapes.AddPicture(FileName:=ActivePresent ation.Path & "\Public.bmp", LinkToFile:=msoTrue, SaveWithDocument:=msoTrue, Left:=500, Top:=100, Width:=150, Height:=50)

End Sub

But this only works when I'm working on it as the macro enabled template.
When I open it from the folder to work in the document as a normal user, it says this:

The macro cannot be found or has been disabled because of your security settings

And now it even says while I haven't changed a thing: specified file not found

Can anybody help me with what I'm doing wrong?? Thanks!!