Adding a stroke to an object

[ladyinblack1964]

Let me preface this by stating that I limp along in Illustrator. I'm trying to place a couple of images and add a stroke around them. The first image, I am getting an error message when I try to place this PNG. In the second image, I am getting extra stroke lines. I'm pretty sure I cleaned up the image in PS before I saved it as a PNG. What can I do differently with these images? Is there any way to remove the extra stroke lines if I can't clean up the PNG further? Thank you!

[meganchi]

I would suggest opening your png up in Photoshop, add another layer beneath the flower image and fill it with a solid color (such as green) so you can see where you have extra lines that need erased.

[ladyinblack1964]

Thank you!

I tried using the Eraser tool to remove the lines and it did not work. Now I am trying Quick Selection and it is not grabbing the lines.

What am I doing wrong?

Is there any other way to see these lines when I'm using the Quick Selection Tool to get rid of the background initially?

[Anna Lander]

Do you know how to use Pen tool in Illustrator? If yes, you can cancel the Stroke effect.
You can draw the path around the flowers, select both objects (path and image) and create a clipping mask (Object > Clipping mask > Make).
Then select the path using Directional Select Tool (white arrow) and set the stroke as you want (color, width, aligning etc.)
this case all unwanted details around the flowers will be hidden and not mess your art.