Hi Fleagle8t,
In addition to jingyi.liu suggestion, you will often see & vblf & used to get the same result:
MessageBox.Show ("Line1" & vblf & "Line2", "My Message")
As an added note, I often like to use a space and underscore in the code to add a line return in the code, for example:
MessageBox.Show ("Some text here used for Line1" _
& vblf & "More text here used for Line2" _
& vblf & "More text here used for Line3" _
& vblf & "" _ 'nothing for line4
& vblf & "More text here used for Line5", "My Message")

Using vbNewLine will work also:
MessageBox.Show ("Some text here used for Line1" _
& vbNewLine & "More text here used for Line2" _
& vbNewLine & "More text here used for Line3" _
& vbNewLine & "" _ 'nothing for line4
& vbNewLine & "More text here used for Line5", "My Message")
I hope this helps.
Best of luck to you in all of your Inventor pursuits,
Curtis
http://inventortrenches.blogspot.com