Where is the YaCy search portal?

There is no public YaCy search portal! The idea of YaCy is to have a distributed search without a centralised server and if there were a central Web portal, that would ruin the whole idea!

A portal-like access to the YaCy network 'free world' (the default YaCy network for the WWW) should at least reflect the decentralized nature of the YaCy project. There are two options that support this decentralised paradigm: search a selection of network peers using code local to the user's browser so that the search does not rely on a central server (as done by peer-search.net) or arbitrary selection of a demo peer by the user:

peer-search.net - the browser as local search engine

yacyweb.de - list of active peers, each can be Demo-Portal

Operating your own search peer is to the best way to use YaCy.

Operating your own search peers is the best option to use YaCy. All arguments for a decentralized search about privacy and censorship resistance will apply and your own peer offers probably the best search performance.