Hey Nandystam! You're starting off with macro exactly the same way as I did! That lens should be a very good tool for learning : )
+2 to Jeff. The color of the rose seems to have lost its saturation due to overexposure.
Also, try playing around with depth of field, it is often the most efficient tool when doing macro. This is entirely subjective I think, but in my opinion you've focused on the "wrong" part of the rose in the last picture. My eyes are drawn towards the stilk, although it's the rose that's pretty.
A thing I find very neat for outdoor macro is an external flash. Using this you can get your motive in focus, and darkening the background a lot. I might be lying, but I think I used that setup in
this shoot. Here I also used the same Vivitar as you're using. It's not in any way perfect, but it gives you a feel of how stuff looks with it.
I think you're off to a good start! Macro is a lot of fun, especially trying out new techniques etc!