: In the Properties panel, set the Fill to None and the Stroke to White . A stroke weight of approximately 20 pixels works well for a standard portal.

: Add a Gradient Map adjustment layer above your background. Set the colors to your neon hue and the blend mode to Screen .

: Double-click the layer to open Layer Styles . Apply an Inner Glow with a Screen blend mode and choose your primary neon color.

This is the most critical step for realism. The portal must cast light on its surroundings:

: Use the Ellipse Tool (U) while holding Shift to create a perfect circle.

: Duplicate your top ring layer and go to Filter > Distort > Ripple . Set the amount to 500% and size to Large to create jagged energy lines.