need help wiring a light fixture?

The red wire is for the light when you have a ceiling fan with a light kit.

Not enough information.

On your fixture: the two whites should be connected

together to the white, (neutral), wire.

The two blacks should be connected together, and to

the line from the switch to your fixture.

In your 'J'Box: You offer two possibilities. Black and Red.

(Don't assume that the black is correct for the fixture.)

If there are both a Black and a Red wire in the box,

it is part of a 'feed through' situation.

There must be other wiring passing through that box.

If you describe it we might be able to help more.

It is possible that the Black is 'Line` and the

Red is a switch leg to the fixture.

If it worked before, everything was connected somewhere.

Use a test lamp to determine which wire should

feed your fixture and which is 'feed through'.

In north america, the red wire is the other hot side of the line.

White is the ground return or cold side of the line.

Black is the hot or switched side of the line.

All your white wires should be commoned together.

You could put one black of the fixture to black in the box.

You can put the other black fixture wire to the red in the box.

You need to check the switches, if any, for that outlet.