Presumably you're after mass-gaining, and while it's possible just with body-weight and those dumbbells it won't be for very long (especially if you're already fairly strong).
Pull-ups, pistol squats (while holding dumbbells, if you can), weighted pushups, standing dumbbell shoulder press, all good options.
Isolation exercises won't mess you up unless you do too much on a single muscle. At the start, though, compound exercises will do more for you.