If I have invented something, how can I get it patented and represent it at world level?

I would add to the two previous comments that filing a national patent followed by a PCT is also a smart way to postpone costs.

As a rule of thumb, filing a patent in major countries (think USA, EU, China, Japan) will cost roughly 4-6k.

If you file a bunch of patents right from the start, you will have to pay that for each country. If you fils a PCT, the deadline for that payment is postponed by approx 30 months, which gives you more time to find additional investors in your idea.