I just feel to big on the bike
If you were fitted for the bike, then go for it. If you havnt been on a bike in a long time, take things easy. It isn't a race. Slowly does it. If you can only manage to go to the bottom of the road then so be it. Gradually go a bit further when you feel comfortable to do so.
There is a great ap called my fitness pal in the Google play store. You can use it to help you to lose weight if that is what you want.
Don't worry about what you look like. There are lots of big cyclists. Get out there, have fun, and enjoy the fresh air.
Forget about everyone talking about losing weight etc. Just concentrate on having fun on you're New bike, then you can go from there if you want, and good luck.