just wan to know to make my forearm strong im doing barbell curl and dumbbell workout so can anyone give me tips how to workout for my forearm using dumbbell

This seems like an easily Google-able question man did you try asking uncle Google first?

Anyhow, using dumbbells? Grab the heavier pair of dumbbells you can hold on to for a good 5 seconds. Stand up with it and walk for as far as you can. That's farmer's walk. It will give you huge forearms. You can do isometric holds. Again, grab the heaviest pair of dumbbells you can hold on to for 10 seconds. Now, stand up with the dumbbells in both hands and hold on to that for 20 seconds.

i can ask Google but maybe some gym guys have their way thats y i ask here too anyway thanks for your info

My favourite;
-Kroc row
-Farmers grip

Some will say Kroc row is overhyped. I think the same before that. But now my grip is really improved. Placebo or not, it works for me.

Protonated grip ez bar, dumbbell curl according to gym rats. for me, loaded carries and isometric hold especially heavy dl session.