How to accept payments on the site?

I made a website for my training course and I would like to accept payments from different countries
tell me what should I choose a payment gateway PayOp, 2chek, PayDo?

Depends on what your target audience uses and trusts.

Btw - moving to Random, since its not a job offer.

Here is the website with more than 245+ payment gateways with reviews and pricing , you can choose for your business according to your requirments.

Thank you