I have got my USA bank account, I dont know much things about online payment system, I want to accept credit card online, what should I do now?

you need merchant or 3rd party merchant to accept credit cards online. use search of this forum as the topic already has been discussed a couple times.

There are lots of options out there.

Popular ones include Paypal.
2checkout.com
worldpay.com

Theres more and more

I have got my USA bank account, I dont know much things about online payment system, I want to accept credit card online, what should I do now?

hi. if you are a newbie that not expert in technical, then start with paypal. the setup is easy, and startup cost is almost free.

once your business pickup, you may switch to 2CO.

when you are going big. you may consider to go for verisign or worldpay as well.

i help a client setup the integration to worldpay before, not that easy, due to many procedure & approval requirement before your site can launched.
furthermore the startup cost, and monthly cost is very high. use this if your sales are above 10k/mth for example.