How should I go about? I am very new to Solidworks
Solidworks excels in designing mechanical components like gears and engines but isn't suited to organic shapes such as a human foot. I feel you would be better selecting a polygon based modelling tool such as Maya (or blender if you prefer open source).
If you are set on using Solidworks for this task you will be best using the surface features available. There are many tutorials on youtube.
You may also be interested at looking into the 'Power Surfacing' plugin from npowersoftware. This is a great tool for creating complex surfaces natively in Solidworks.