How to Find a Portal in No Man's Sky

only thing you will need is gek relic, korvax casing or a vykeen dagger - this depends on star system

you will need to buy few planetary charts in the space station

go in space and activate chart

now when you found a monolith you can interact with it
- it will ask you a question like this one:

- after you answer it you can interact with it again

(if you cant then find another monolith)
- after you interact with it again, you will se this:

and you will be able to locate a portal

now you found a portal you will need to input glyphs for a system you are looking for