I have no idea how to play a Rogue and I am at a complete loss

[Reaptor]

I grabbed Astarion, and combat starts and I hide, but they just see him immediately. I'm not sure what to do with him and the only reason it feels like I have him is to open doors.

[Isahn]

Rogue's feat is sneak attack.
To be able to land one, you need to be in position of fighting with an advantage.
There are a couple of ways to do that :

- Attacking a target while being hidden (hard to do middle of a fight)
- Attacking a target that is within 1.5m of an allly (let him assist your tank)
- Attacking a Prone target within 3m (any disable works)
- Attacking an enemy that is Restrained
- Various spells / cantrips / abilities / things that grants advantage

This means that playing with a bow, while not a bad idea won't do much compared to playing in melee as a flanking character. But you need to flank, otherwise he's just your average guy

[Lamp]

You can also use that bonus action sneak and then make a full sneak attack as long as you're not in the line of sight of any of the enemies (or right beside them.)

[TheMasterBlaster]

rogue is not very noob friendly. use Laezel or make your own Fighter until you have enough time to learn more about the game mechanics. if you don't know anything about DnD5e, then you should at least watch some BG3 gameplay guides.

[VoiD]

Honestly, forget about sneaking, hold shift and avoid line of sight cones, hide when they can't see you at all, then attack people from behind.

If you're in combat just move another character near your target first, then do your own sneak attacks.

PS: Assassin and thief are good classes to multi with gloomstalker ranger, the synergy is pretty neat for both melee and ranged
PS²: Dual Wielding sucks in this game, you can make it work, but it's always the worst option, specially when everything you want to use every single turn also costs a bonus action, so you'll probably never hit with your offhand attack.

[Kyutaru]

Learn to stealth mid combat. You can restealth by breaking line of sight with enemies, hiding in darkness, using obscuring fog clouds, or just being so high up that no one can see you. Height advantage ftw. But anyway, your stealth skills will improve as you level and you'll be able to ignore enemies looking at you more often. Early on though you want to on your turn move behind cover, stealth, move back out of cover and snipe someone with sneak attack. Keep practicing the ways to stealth and you'll get the hang of how to make him useful.

[Poddy]

And you must press Shift. That marks the line of sight in Red from enemys.

[Noctoculus]

No matter you stealth skill, hiding in full light will fail if you're in someone's line of sight.

[†WeedZebra†]

gotta hide where they arent looking directly at you.

[cfehunter]

If you hold shift it'll show you the vision cones of the enemies. (no idea what the gamepad equivalent is).

Move your rogue out of the cones and use the cunning action version of hide (it's blue), that makes it use your bonus action instead of your action, then fire a sneak attack.

You can also just sneak attack any enemy that's in melee range with one of your allies (summoned entities count). The rules for sneak attacks are way more lax than backstab was in AD&D2e or Baldurs Gate 1/2.