Which and how many stamps should i buy to send a package from uk to overseas? Please try to answer in detail?

"Overseas" is a pretty broad destination. You didn't tell us the dimensions and weight of your package either.

We do not have ESP.

Take your package to the post office. Those people are paid to help you.

In many places you cannot ship a package with stamps unless you ship it from the post office anyways.

No weight then so how Should we know. Take it to the post office as we all do.
UK

you need to take your parcel to the post office, you can't determine how many stamps on your own to put on it
there will be differences in the amount it costs depending on where it is going

take it to the pot office, have them weigh it and put on the proper postage.

go to post office, repeat your question there

How can we give you a detailed answer when you provided no details in your question?

Take it to the Post Office and they'll weigh it and tell you. You post the amount and they'll get it on it's way.

The Post Office website has all the details you need.