The graphene install docs is in your language and will walk you through the install process. Their support page points you to discord, telegram, matrix support channels as well.
https://grapheneos.org/install/
https://grapheneos.org/contact#community
As a general rule anyone that asks for a non-proprietary thing that will do everything their proprietary thing does without alternative solutions allowed is so far from the reality of non-proprietary software in a proprietary world that they can not be made happy so I'll leave the support of that to others.
"Imagine browsing without trackers following you everywhere or your phone’s performance lagging because of ads. That's the kind of freedom GrapheneOS promises."
It's hard to take the sales pitch seriously after such disingenuous statements such as this. The OS itself doesn't serve ads, but rather the apps you install and the web pages you visit. As well, as soon as you browse the web or install one of your most loved popular apps, you're being tracked. For the average user, the one that wants to use the same apps on the gOS OS that they do on stock android, they will be faced with basically the same ads and the same tracking.