Hm. Best to start off simply, then. Either get a 1st-level adventure from an old issue of Dungeon Magazine, or throw something simple together yourself.
Example: The PCs are neighbors in a small town, and goblins have started causing trouble lately, waylaying travelers heading towards the town. Though several goblins have died in the process, many farmers have been slain while trying to bring their foods to market, and so too have a few merchants that were bringing common trade goods.
The town can't allow this to continue, but all the town's usual protectors are out of town right now, as the militia was called into service by their local lord to deal with another threat. Only a minimal force of guards, mostly green recruits and old men, are still active in town at the moment. So someone in town (the mayor, the elder guard in charge, an important local merchant, or an old farmer who's ticked off that the goblins have killed a few of his old buddies) tries to rally a few people with the guts to go out and deal with the next goblin attack.
Going out of town, after a bit they find a pack of goblins attacking a merchant heading for town, and the few guards protecting the merchant. So the party goes to the guards' aid. The guards would just be ordinary 1st-level warriors, and probably overwhelmed by goblins, if not for the PCs arriving. After a bit, the guards manage to defeat the goblins, thanks to the PCs' help. Though the guards might actually die during the fight, so long as the goblins consider them to be a bigger threat than the PCs, they should concentrate most of their attacks on the merchant's guards. Then the PCs can escort the merchant to town or something, and get a reward from him.
And maybe they can learn where the goblins came from, to go after their lair or whatever, after the PCs have recovered from the fight. The lair might be a small cave nearby, and might have a few simple pit traps or the like (if the party has a rogue, to find and deal with the traps). But most of the goblins probably aren't in the lair, actually out and looking for other people to accost. So the PCs fight a few more goblins, then......well, whatever. I dunno.
There's just one possible, rough idea that came to mind.
Maybe instead the PCs just get a treasure map from a mysterious stranger, and go to find the treasure in some ruins a few weeks away. Fighting some monstrous spiders, a few squatter kobolds, maybe a feral housecat
, and a dire badger in the bowels of the ruins (not all at once of course!), where the paty finds some treasure. Be sure to stick a hidden door somewhere around there, too, just in case the party might find it. It's always neat to find a hidden room or compartment with some treasure or other stuff in it.
For a twist, maybe the 'mysterious stranger' shows up after the group gets into the ruins, after they've dispatched the 'squatter kobolds' that were actually supposed to be in waiting for them. Then the stranger tries to slay the PCs and take
their possessions. Then maybe they find out through clues inside the ruins that they had been used as a hideout by this bandit dude, a place for him to lay low and stash his treasure, but also someplace he could lure in poor chumps to kill.
