Ok I just took out an old murray 8 breaker main lug panel that was being used for a main breaker box for an apartment and installed the Homeline 100amp load center from home depot. My question is with grounding and bonding of the neutral. There is no disconnect before the panel and there are 3 wires coming in directly from the meter (service Entrance Cable)and a separate ground coming into the panel from a rod in the ground. Now with the new box I put the 2 hots in their lugz the neutral to its lug and the ground I connected to a ground bar kit I installed in the new panel. Here is where my question comes in. Its my understanding that the ground and neutral should be bonded where a main disconnect exists. I installed the green bonding screw that comes with the panel box assuming that the screw connects the neutral bar to the panel and the panel to the ground bar I installed. As I look back I guess I didn't have to buy the ground bar kit or install the screw if I just bought a lug to attach to one of the neutral bars and run the ground right to it. Please let me know if I'm on track or way off. If you have any other questions let me know.

You are correct. In the main panel the neutral buss is grounded. However you didn't do anything wrong. As long as both the neutral and ground bars are bonded to the panel, you are OK.

Yes they are and thank you for your help. Ive done a lot of reading the last hour and I now understand much more of how and why you do bond at a main disconnect and do not bond in sub panels.

There is some good info in this sticky: https://www.askmehelpdesk.com/electrical-lighting/grounding-bonding-surge-supprression-386501.html