I would recommend taking a guess at how big an area you want your map to represent. Are those blobs little islands in an archipelago or are they continental-scale features? The overall scale of you map will determine what to show in the next step: locating the general highlands (or mountains) and major waterways. The scale will also help you in determining what kind of projection you need (assuming a sphericalish and not a flat world). The larger an area that your map represents, the more distortions will appear as the map is drawn on a flat surface.

Once you have a scale and some rough topography, locate your equator. That will help you to figure out the temperatures and rainfall for the rest of the world. As Diamond points out, you'll undoubtedly want more blank space around the edges of your land areas for adding things like scale indicators, borders, and other annotations. You might also want some extra oceans to help balance things out visually.

I also recommend posting images as PNG rather than BMP, because BMP files are quite large and don't have universal browser support.