Assuming your text is in your document, and you insert a picture. While the picture is selected, you will notice that on the right format panel, the Arrange tab has appeared. Select either Stay on Page, or Move with Text — depending on your image goal — and then look at the Text Wrap feature. By default, once you drop a picture into the document, it is set to Automatic. This means you can place your pointer in the image and just move it around, while text flows around it. The smaller the image the better the flow effect. This is a discussion about Pages v5.2.2, but it will work the same in v5.5.
Let's say you want the image flush aligned to the left margin, but want text to flow above, to the right, and below the image. Change text wrap automatic to Around, select the right icon for Text Fit, and adjust your spacing up or down for the proximity of the text wrap to the image. It looks like this with Text Fit spacing set to 9 pt.
