I will assume you are using Inkscape for this, as per your other questions. You should tag your question with Inkscape if this is the case.
Place an image in position under the heart, lower to the bottom using the shortcut End to do that.
Draw a rough path with the pen tool around the the heart. It doesn't need to be exact, as long as it is inside the black lines of the heart shape, since the black outline of the heart will cover over the rough edge anyway.
Select both the path you just made and the image (hint: hold down Shift while clicking both objects to make a multiple selection), then do Object > Clip > Set clip