You don't need the cream. Go and buy some padded shorts to start with, look for
dhb, which is the own brand on the
Wiggle website; their gear is great value. Wear the shorts next to the skin, not with pants underneath.
Then get the saddle set up correctly; the shop who sold you the bike should do this for you or your local shop should be able to do it. For most blokes this means canted up by a degree or two at the nose so that your sit bones are "cupped" by the saddle and a little weight taken between the legs. If the saddle is too high your pelvis will be rocking, which will make you sore. To get the saddle positioned right on the rails start by putting the point of your elbow against the tip of the saddle and adjusting it so that your middle fingertip is touching the small bolt in the middle of the steerer. Make sure the handlebars aren't so high that you are sitting up and putting all your weight on your saddle.
It wil get better as you lose weight and become accustomed to the saddle.