How the heck do I paint this?

[TheOrigRights]

I need to paint the wood gloss white. It's part of the door frame.
How do I not get paint on the shower wall panel to the right of the plain wood?

nb. I am not very skilled in these things.

Thank you.

Masking tape or a painter’s George

Masking tape - I find the blue one is very good. Maybe do a couple of straps next to each other to increase the width covered.

Masking tape over the bit you do not want covered in paint.

Frog tape, green or yellow, I prefer the yellow one. Get it on Amazon or at Homebase/b&q

I understand about masking tape, but will I be able to apply it such that I can still paint the tiny gap between the wood and the panel? I'd need to poke it between the two - which seems sticky and difficult.