First double click on the image in layer window then name it and click on OK. Now if you use magic tool on the image and delete the background, it will also delete some of the image part. So to fix it you need to find that kind of places of the image and use brush tool to fill up that space. Now you can delete the background by selecting it with magic tool. Now if you want to set a new background, go to layer, new, layer and drag this new layer under your image in the layer window. Now you can paint this new layer whatever color you want. You can also give some effects to your image by clicking on the layer, layer style, drop shadow or stroke etc. Now if you want to insert text, type it and to set it right, click on wrap text icon and choose arch, bend it to the any direction you want, size your text and set it. You can also give drop shadow effect to your text by the same way.